Outposts of Empire Britain's Treasure Islands

My name is Stewart McPherson. I am an explorer and naturalist.

I have climbed dozens of unexplored mountains

and discovered many new species.

And yet the journey I have always wanted to make

is to the most remote parts of Britain.

And I mean remote.

Not the islands of Scotland or the mountains of Wales

but the UK overseas territories.

14 islands and archipelagos scattered all across the seven seas.

They have seven times the land area of the UK.

Some are uninhabited but 350,000 people live on the others -

people who have voted to remain part of the United Kingdom.

I read about these far-flung places when I was a child

and this was my treasure map.

Not to hoards of gold and silver but something even more special.

Untold riches of wildlife and unique cultures.

I wanted to stand on the biggest penguin colonies on the planet.

I wanted to dive on the world's richest coral reefs.

And I can do all that without leaving Britain.

No single person has ever explored all 14 overseas territories and

that is just too much of a challenge for any explorer to resist.

So I'm going to follow my childhood treasure map,

right the way across the globe,

to discover the furthest reaches of Britain.

This journey will take me to eight of the UK overseas territories

which were once important military or trading bases.

And some remain as such today.

I will visit the remote islands of Ascension

and Saint Helena in the Atlantic...

..Gibraltar and Cyprus in the Mediterranean...

..but first, five territories scattered around the Caribbean Sea.

My journey begins in the wake of perhaps the most famous

explorer of all - Christopher Columbus.

October 12th, 1492.

Three Spanish ships anchored off the coast

of an unknown tropical island,

waiting for dawn and a chance to explore.

Columbus was about to set foot on a new world.

This place was teeming with strange and colourful plants and animals...

..the likes of which he had never seen.

The Caribbean is a biological hotspot,

one of the most diverse places on the planet.

But the world that Columbus found would soon be changed for ever.

In 1493, he came back.

One of the stops on his second voyage was here on Great Tobago

in the British Virgin Islands.

This time, he brought 17 ships, full of livestock, crop seeds

and 1,500 people.

His voyage was the first attempt by Europeans

to colonise the Americas,

a move that would create the people, the maps and places we know today,

and for ever change the landscape of the entire planet.

Other Europeans followed Columbus

and these islands were quickly transformed.

Today this is how most of us think of the Caribbean -

azure waters, a tropical paradise.

But many of the creatures that greeted Columbus have vanished,

or are so rare

they are only just hanging on

in a few out-of-the-way places.

On my journey around the Caribbean territories, I'm going to find

those places and meet the people who are helping these animals

fight for survival.

Beginning with Columbus, the Caribbean's plants and animals had

to face hundreds of alien species and the invasion is far from over.

I have arrived at the second of the Caribbean territories -

the Cayman Islands.

Another tropical paradise, or so it seems.

Beautiful reefs, a home to spectacular corals and fish.

But one fish doesn't belong here.

I am diving with Bradley Johnson,

from the Cayman Islands Department of Environment,

looking for the Caribbean's latest alien invader.

And it doesn't take long to find one.

A lionfish.

It should be living on the coral reefs of the Pacific but somehow -

nobody knows exactly how - it was introduced into the Caribbean.

A voracious predator, it devours the native fish,

pushing some close to extinction.

Lionfish were first seen here in 2008, but now, in places,

they make up to 80% of the fish population.

And none of the local top predators will touch it.

So why don't local species prey on the lionfish?

First of all, it is because they are not native to our waters.

The largest species that normally prey on reef fish, like the snappers

and the groupers,

don't recognise the lionfish as something they can eat.

Another aspect is that they have venomous spines.

They have 18 spines altogether.

13 spines across the top

-and then five additional spines across the bottom.

-Wow.

How powerful is the venom?

It is not fatal but it gives you a very nasty, very painful sting.

Really?

But there is one predator that might help -

us.

Commercial fishermen have joined conservationists to hunt

the reefs for lionfish.

The spines are so venomous that the

lionfish are collected in plastic buckets to protect the divers.

Stripped of their venomous spines, they are perfectly edible.

And local people are now encouraged to add these fish to

traditional West Indian cuisine.

So, how good is lionfish?

There's only one way to find out.

West Indian lionfish chowder.

-Thank you very much.

-Enjoy.

-Thanks.

The lionfish is, of course, the perfect eco cuisine.

The more lionfish we eat, the fewer there are out on the reefs.

And, of course, the more we eat,

the fewer other endangered species, such as grouper,

that end up on the tables.

So it really is the perfect eco, greener-than-green choice.

So eat 'em to beat 'em.

Lionfish are very tasty.

And the more people that agree with me,

the faster we can eat the alien lionfish into extinction.

It should work.

In the past, it has been far too easy to eat native Caribbean

animals to the edge of extinction.

The queen conch, a Caribbean native prized for its flesh by local

Indians long before Columbus arrived.

The conch are large, slow-moving and very tasty. A recipe for disaster.

And they once existed in numbers that defy imagination.

In some places, Indians constructed huge artificial islands,

many metres high, entirely out of conch shells.

Big enough to build whole villages on.

Yet when the first Europeans arrived,

there were still uncountable numbers of conch in the water.

These islands are more recent

and tell a story of impending disaster for the queen conch.

This entire island is made out of these spectacular

queen conch shells.

This is actually an endangered species

but they are plentiful enough in these waters to be harvested,

as long as it is done sustainably.

You're meant to catch these adults with these big flat flanges

and that shows it is an adult capable of reproduction.

The problem is, many of the ones on these drifts are these babies

that don't have that flange. That shows they are juvenile.

When you start taking these out of the populations,

then the whole system is heading for collapse.

There may be a solution to this problem on the next territory

that I visit.

The Turks and Caicos Islands.

This pioneering project is breeding conch in captivity.

In the wild, most young conch die, but here they survive.

First they are raised in tanks, and then in sea pens,

grown big enough to have a better chance of surviving in the wild.

Thousands are released and the rest can be sold for meat,

to take the pressure off the wild populations while they recover.

And these huge molluscs have become an unlikely tourist attraction.

Did you touch him?

I already did.

These farms, along with marine protected areas,

might be enough to save the conch

but some Caribbean animals are much closer to the brink.

Back on the Cayman Islands,

these forests were once home to an amazing animal.

A Grand Cayman blue iguana.

But why isn't it blue? First thing in the morning, it is too cold.

It needs the Caribbean sun, and as it warms up, it gradually turns

an unusual shade of blue.

But it was hunted for food and killed by introduced predators.

And by the start of the millennium, there were hardly any left.

It seemed the blue iguana would follow many other unique

Caribbean species into oblivion.

But not if one man could help it.

This is Archie and he is helping Fred Burton

and his team rescue his species.

With almost no funding, Fred has set up an iguana breeding station

and it is an amazing story.

20 years ago, I could not just show you the blue iguana like this.

-They were, to all intents and purposes, extinct.

-Really?

We didn't know where they were, we didn't know where to find them.

We caught it just in time

and we managed to get together 20 different individuals from the

original wild population, some from cages, some rescued from the wild.

We started breeding them here on a small scale

and then it really started to pick up.

Now what we're doing is...

we're actually hatching 100 young blue iguanas every year,

rearing them until they're two years old

and then putting them out into protected areas.

-That's amazing.

-Hello!

I think he is eyeing up your blue shirt, Stewart.

-It is almost an iguana colour.

-Yes!

So now we're up to about 700.

Hopefully, in another few years,

we will hit our target which is 1,000 in the wild.

When we reach 1,000, we don't need a captive breeding programme

any more and Archie can join his offspring in the wild.

His future is very bright.

Yeah, and I really look forward to the day

-we can close this whole captive facility down.

-That's great.

-Let all these iguanas go.

-Back into the wild.

-Yeah.

The Caribbean is full of unique creatures,

each evolved in isolation on its own island.

And there are so many islands in the Caribbean.

It is one of the most diverse places on the planet.

But why are there so many islands?

I am on my way to Montserrat to find the answer.

Montserrat lies in the Lesser Antilles, a chain of islands

that mark the boundary where two of the Earth's

great tectonic plates collide.

As they do, they push up volcanoes which create new islands.

This is how Montserrat was born.

And, in 1995, its volcano erupted again.

The volcano spewed out devastating pyroclastic flows.

Torrents of superheated gas and dust that race over the ground.

Too fast for anything to escape.

20 years later, some parts of the island that bore

the worst of the pyroclastic flows, are still scenes of desolation.

Much of the southern side of the island is now a barren ash field.

And the capital of Montserrat, Plymouth,

was directly in the path of the falling ash which buried

the town up to the level of the roofs.

The same kind of eruption from Mount Vesuvius buried Pompeii

and Herculaneum, and walking around Plymouth today

feels like walking through a modern version of Pompeii.

The force of the eruption is almost impossible to imagine.

But I have met up with Mapai, who saw the eruptions first-hand.

He is taking me back to where he used to live.

Stewart, some people think it is just ash, pyroclastic flows,

but look at these boulders.

They pelt down from the volcano, down this valley.

-These huge rocks here?

-These huge rocks.

Can you imagine that? Destroying everything in its path.

The homes, the villages and then came this widespread fire,

-which we call the surge, which burnt all the vegetation.

-Really?

Look at some of the charcoal that has been left behind.

It's an indication...

That is how the trees got burnt

and turned into charcoal.

The saddest part is that the villages that were

-here are buried under us.

-How deep are they?

About five metres below all of these pyroclastic flows.

-These are people's homes?

-These are people's homes.

-And right where we are standing is where I am from.

-Really?

But even a volcano can't quash the Caribbean character.

There's always a bar somewhere close and a friendly barman.

That's what friends are for!

-Wednesday, Thursday, Friday?

-Wednesday, Thursday, Friday.

Come on.

Most of the islands have been developed.

To me, they look like the front covers of exclusive

travel brochures.

But the vibrancy of real life here, of nature,

has mostly disappeared.

I need to get off the beaten track,

to get a glimpse of what the Caribbean should look like.

SEA BIRDS CALL

This is Dog Island, off the coast of Anguilla.

It is one of the most important sea bird colonies in the Caribbean.

But, like many islands, it had a population of black rats

which fed on sea bird eggs and chicks.

After a campaign to get rid of them,

in 2014, Dog Island was finally declared rat-free.

I would love to come back in a few years.

It could be even more spectacular than it is now.

Brown boobies fill the air

and magnificent frigate birds ride the tropical breezes.

Magnificent frigates occur right across the Caribbean.

On Dog Island, they have a safe home to breed.

But elsewhere they face a sinister threat.

Such as here on Great Tobago in the British Virgin Islands.

They nest in low bushes.

But the bushes are draped with the corpses of frigate birds.

And this is why.

Nylon fishing line.

Birds fishing at sea get caught up in discarded lines.

And when they land back on their nesting tree,

the line gets tangled in the branches.

The bird dies a slow death.

And as the nylon lines never decompose,

the nesting trees soon become deadly traps.

I'm off to join a team of volunteers who try

and free as many of these birds as they can.

But it's not easy.

Frigates have very sharp bills.

You want to watch their beak.

Is his beak caught? Is that why he's up here?

The line is tangled around so many branches.

I can see why it's lethal to these poor birds.

OK, it's the other foot. Oh, look, it's cut!

Now what we have to do is remove the noose of line around its leg.

It's obviously stressful for the birds, but without our help

they wouldn't stand a chance.

-Poor little fella.

-I know.

He's got a fighting chance.

The Caribbean territories are fairly easy to reach,

but the next islands on my journey are much more remote.

Ascension and Saint Helena lie in the centre of the Atlantic.

Ascension is a military base with regular flights by the RAF

from a base in the Oxfordshire countryside.

But Ascension couldn't be more different

from England's green and pleasant land.

A barren volcano just a few degrees south of the Equator.

And about halfway between Africa and South America.

The island as been described as hell with the fires put out.

And my first steps here felt like walking across a landscape

on Mars, rather than a part of Britain.

The Portuguese discovered Ascension in 1501,

but it looked so unpromising, they never colonised it.

And you can't really blame them.

This jagged lava shoreline

pounded by Atlantic surf wasn't very inviting.

But in 1815, the British garrisoned the island.

This uninviting spec of land had one big advantage.

Its strategic position right in the middle of the Atlantic.

It was used to house stores for naval and merchant vessels

on long sea voyages.

And some of those supplies are still here.

But Ascension was more than just a supply depot.

Despite appearing so barren, Ascension provided its own harvest.

One which just crawled onto the beach, but was easy to catch.

Green turtles.

From the 15th century onwards,

turtle meat fuelled the growth of Europe's empires.

And when it was discovered in the 16th century,

Ascension had one of the biggest green turtle colonies in the world.

One reason why Britain claimed the island.

But there was a problem.

Green turtles only climb onto the beaches for a few months each year.

These walled enclosures provided the solution.

These vast ponds were built so that a stock of live turtles

could be kept ready for any ship that called into port.

Once the turtles has been caught on this beach, this winch

could haul them up and they could be kept in here, ready to be sold.

The turtle population was almost annihilated.

The trade in turtle meat has long since ended

and the turtles are now strictly protected.

Fortunately, enough of the turtles survived

and the population is now recovering.

And they still nest on this very beach

where they were once killed in huge numbers.

They crawl out of the sea under the cover of darkness,

when it's cooler and they won't overheat,

as they haul themselves onto the beach.

They're looking for somewhere to dig a nest.

I can see... Yeah, right there!

As you can see, she's quite a powerful digger.

Those flippers are very strong for swimming through the ocean

but also for moving sand.

With each flipperful, she's moving a kilo or two of...

HE CHUCKLES ..of sand.

And very quickly digging a very deep hole.

The population has now recovered

and is the second-largest green turtle

breeding colony in the Atlantic.

Over the season, on this one beach alone,

around 10,000 nests will be dug and filled with eggs.

Most finish their task

and return to the safety of the ocean while it's still dark.

But a few are still returning as the dawn breaks.

Now the struggle to reach the sea becomes more urgent.

It won't take long for the heat of the day to become lethal.

And some get into real trouble.

They wander into the jagged lava at the edge of the beach

and are now stuck.

This girl here obviously was trying to get to the water,

but just didn't count on finding these sharp stones and rocks here.

If we left her, the sun, as it comes up,

would just cook her in her shell.

And the problem is that...

Yep!

That's a 300-kilo adult, so I can't lift her on my own.

'Luckily, groups of squaddies from the local RAF base

'join conservationists in early-morning turtle rescue squads.'

-Come on!

-You all right?

Yeah. That's it.

'Instead of eating the turtles,

'people stationed here now help save them.

'Though it's not easy.'

Oh, there's one!

There's a load more down here, they can have up to 11 each day.

So it's a big task.

Have you got...? Oh, you've got one. Keep going.

Don't drop her, don't drop her. Keep going, keep going! Oh!

'These turtles are so much heavier than they look.'

Keep going, keep going.

And she's away!

That's one exhausted turtle. Good luck to you!

Back in the early days of exploration,

the other thing that passing ships needed was fresh water.

The parched slopes of Ascension don't look very hopeful.

But when the Royal Navy garrisoned the island,

a regular supply of fresh water was vital.

Yet there's plenty of fresh water here.

In the form of mist condensed from moisture-laden winds

blowing over the high Ascension peaks.

All it took was for two free-thinking visitors

to invent an unusual solution.

Charles Darwin called in here as he travelled the world in HMS Beagle.

Then later, his good friend,

botanist Joseph Hooker, also came to the island.

They thought that plants could wring water out from those clouds

and they persuaded the British government to send

all manner of plants to this barren volcano.

By the 1850s, the plants started to arrive.

They came from Kew, all across Europe,

South Africa and as far afield as Argentina.

And they were planted on this mountain behind me.

Although they don't normally grow together, the plants

quickly formed natural-looking layers up the mountain.

The first layer on these dry lower slopes

was made of these eucalyptus trees from Australia

and these succulent cacti from South America.

It's hot and semi-arid.

Halfway up, it's much wetter

and home to these tropical rainforest trees

and bananas from Asia.

The upper slopes and the summit of the mountain are much cooler

and they're home to this mossy montane cloud forest.

And it's really interesting that you get these three layers.

These layers occur on tropical mountains across the world.

And the fact that they've developed and stratified like that

in such a short time is just nothing short of amazing.

Even more amazing, this man-made forest

did exactly what Darwin and Hooker hoped it would.

Different plant species were selected to trap more

and more humidity from the air.

This is one of the original ficus trees that Joseph Hooker sent

down from Kew over a century and a half ago.

And he selected this tree specifically because these

highly-divided branches and these long roots are all covered in moss.

And that dramatically increases the surface area

by which the moisture can be trapped.

And the results couldn't be more efficient.

There's been no rain up on this mountaintop today,

but, as you can see, the roots are literally dripping with moisture.

And Darwin and Hooker's experiment has also helped

some Ascension natives - land crabs.

For most of the year, they only live on these mountain slopes,

where there's enough moisture to survive.

Now, the growth of this alien rainforest provides them

with plenty of water, as well as vegetation for food.

But to breed, they must release their eggs into the sea.

And to do that, they'll have to trek down to that distant bay.

A journey of well over a week.

And they'll have to cross parched lava fields.

A deathtrap if a crab is caught out in the baking sun.

They must make their journey under the cover of darkness.

So it's about ten o'clock or so now at night...

The crabs love the night because it's cooler.

And especially after heavy rainfalls.

And actually, there's one right there!

There!

Oh, it's a big one! This...

Come on, you! This is a male.

You can tell by his small tail.

In the female, it's much bigger to carry all those eggs.

And this is about as big as this species gets,

so he's definitely a mature specimen

going down to the beach to meet some lucky ladies.

So let's follow him and see what they're up to.

The males can mate anywhere along the migration route,

so few of them bother to make the long trek

all the way down to the beach.

All of the crabs that have made it this far, they're all females.

And you can see her massive dark eggs supported by her tail here.

They're incredibly enthusiastic and keen to get down to the ocean,

so we'd better let them to it.

The crabs wait for waves to break over them,

then shake themselves to release their eggs.

If they can, they'll hang onto the rocks.

These are land crabs and will drown if swept out to sea.

There used to be huge numbers of crabs living here,

but now the population is much lower.

Today, some are killed on Ascension's roads.

In the past, hundreds of thousands were killed as pests.

But when the first explorers arrived,

they had an even bigger effect on the island's wildlife.

The ships that called here left behind cats and rats and mice.

Originally, the island was teeming with birdlife,

like these sooty terns.

SQUAWKING

These vast bird populations are incredibly vulnerable

and unadapted to cope with introduced predators.

And these sooty terns really demonstrate the point.

All of the birds here nest directly on the ground.

And because their only defence is to peck, to squawk or fly away,

their chicks and eggs were just decimated

by the cats, the rats and the mice.

And, as a result, their numbers plummeted.

Vast swathes of the island that were once home

to millions of birds fell silent.

These white splotches here on the rocks,

this is the baked guano of bird populations

that were wiped out up to a century ago.

But there's one place where I can get a glimpse of what

Ascension used to look like - Boatswain Bird Island.

Still glowing white with fresh guano.

Cats, rats and mice never made it to Boatswain Bird Island,

so this remote outcrop became

a refuge where the last of the sea birds survived.

It's a really hard place to get to,

across a rough channel the locals call Shark Alley.

And it's protected by steep cliffs covered in crumbling guano.

No-one has filmed on this island for 20 years.

But the effort is more than worth it.

Every square metre is packed with different sea birds.

The cliffs are home to delicate-looking fairy terns.

They're blown like scraps of paper on the breeze.

But they're much tougher than they look.

Tropicbirds also ride the Atlantic winds.

This is the boatswain bird, which gave its name to the island.

It's a tricky climb to the top,

but this is what much of Ascension would once have looked like.

Packed with masked boobies.

SQUAWKING

But there is one very special bird here,

the Ascension Island frigatebird.

This is the only place in the world where it lives.

This island is so incredibly important.

When the Ascension frigatebird was wiped out on the mainland,

this is the only place in the world where it survived.

About 10,000 birds live here,

and, without this island, the entire species would become extinct.

Over the last few decades,

huge efforts have been made to clear the main island of feral cats.

And in 2006 it was finally declared cat-free.

And it didn't take long for many of the birds

to reclaim their former home on the mainland of Ascension.

Noddy terns, tropicbirds,

masked boobies and brown boobies.

Everything except the threatened Ascension frigate.

So again, the conservationists stepped in

by making model frigatebirds.

In 2011, these decoys were put here

to try and attract the Ascension frigatebird

back to the mainland from Boatswain Bird Island.

Would the frigates be fooled?

While I was on the island, something very special happened.

In late 2012, two pairs of Ascension frigatebirds

returned back to the mainland.

Of those two pairs, one failed to raise a chick

and the other succeeded.

This little fella here in front of me,

he's the very first Ascension frigatebird

back on Ascension mainland for over 180 years.

Since my visit, many more frigates have bred on the mainland.

Their return, and that of the green turtles,

is a real success story for conservation.

As I prepare to leave Ascension,

the next generation of turtles is also heading out to sea.

It might be 50 years before these hatchlings mature, but when they do

they'll be able to find this tiny speck of land to come home to breed.

My next destination is another speck of land.

The island of St Helena.

I flew to Ascension in just over eight hours

but St Helena is 1,300 kilometres south of Ascension

and can only be reached by ship.

And not just any ship.

This is one of the last working Royal Mail ships -

the RMS St Helena.

We're about to get on to the launches.

So, it's goodbye to Ascension and hello to St Helena.

Royal Mail ships were contracted to carry the royal mail,

and the mail had to be delivered on time.

So, ships bearing the RMS designation were really efficient.

Any ship displaying the crown insignia was seen as special.

SHIP HORN BLASTS

Ever since I was a child I've dreamt about coming on this famous vessel.

The RMS St Helena has a really special place for these

Atlantic territories.

At the moment, it's the only way of getting cargo, people

and livestock to St Helena.

It's going to take three days to sail from Ascension to St Helena.

And to pass the time on these voyages

the RMS St Helena has its own customs and traditions.

One of them is deck cricket.

A classic English scene in the middle of the Atlantic.

Next bowler!

Oh!

Oh, no!

'Sadly, I was never good at sports.'

ALL: Oh!

APPLAUSE

I forgot to tell you.

You're the captain, so for every run you lose by,

-you've got to buy us a drink.

-No way!

It took all three days to pay off my drink debt.

But my first glimpse of St Helena left me in no doubt it was worth it.

We've been steaming for three days,

now I'm finally approaching St Helena.

This is Jamestown harbour just down here in the foreground.

'The people of St Helena, known as Saints,

'are famous for their warmth and hospitality.'

-Really nice to meet you.

-Welcome to St Helena.

-Thank you.

'Robert, the taxi driver, offered to show me around.'

Thank you.

Lovely.

St Helena is the second oldest territory after Bermuda.

Jamestown was founded in 1659 by the East India Company

and its long history can be seen around every corner.

It was granted city status by Queen Victoria.

A British city in the middle of the Atlantic.

'Like Ascension, St Helena was a vital supply depot

'for sailing ships.

'And one of its most important products was rope.

'Made from flax.'

This is where the flax grows, loads of flax.

Down here, I'll show you where some is.

'New Zealand flax was introduced to St Helena

'in the first half of the 19th century.'

'It has tough fibres, perfect for making rope.'

In here is the fibre.

-Right.

-See the fibre there?

-I see, yes.

-This...

-Strong, very strong.

-Very strong.

Very strong. You can see why it's good for making ropes.

Rope making on St Helena reached a peak in the 1930s

when more than 3,000 acres of flax were under cultivation.

But the industry collapsed in 1965 with the arrival of synthetic fibres

like nylon.

All that's left are the abandoned flax mills.

Echoes of a once thriving industry.

Yet, flax is far more than just a historical footnote.

The conditions on St Helena were ideal for the plant

and it soon escaped from the plantations.

The flax plants now cover vast areas of the island.

Many of the ridgetops, such as this one behind me,

are completely covered with flax.

Of course, the impact of that is that many of the native plants

and animals have been completely displaced.

'And flax is just one of many alien plants and animals

'that are changing this unique island.'

The landscape across St Helena

might look green and lush and covered with vegetation,

but what we are looking at is a broken ecosystem.

Pretty much all the plants and the trees you can see here

have been introduced by man.

The original plants and animals, the endemics,

they're restricted to these hilltops,

the last places on the island where they survive.

On these remote ridges daisies grow into trees.

Just one of dozens of unique plants and animals.

Some are now lost for ever...

..and some reduced to just one or two individuals.

One example is the unfortunately named bastard gumwood tree.

This is one of the last two remaining bastard gumwood trees in the world.

There's this tree here and another on the other side

of the island several kilometres away, and that's it for the species.

The entire effort to save this tree from extinction rests on these

two individuals.

The St Helena National Trust

is fighting to save the remaining species.

Dr Rebecca Cairns-Wicks took me out

to the Millennium Forest where native species are being replanted.

Seeds have been collected from the last remaining plants

and grown on in a specialist nursery on the island.

We have got species now that were reduced to one or two individuals,

which are now in their thousands,

planted in either safe, cultivated sites or semi-wild conditions.

And they are doing much, much better

and, hopefully, starting that process

of regeneration for the future.

And as the native forests and grasslands are rebuilt,

there's also hope for creatures that depend upon them.

The spiky yellow woodlouse.

Still only a few hundred individuals left.

Or the wirebird, a kind of plover,

that's become the symbol of St Helena's conservation programmes.

But there's still a long way to go.

Generations of introduced grazes

have stripped the native vegetation from some slopes,

turning them as barren as Ascension's ash fields.

One reason for St Helena's unique wildlife is its remote location.

Animals and plants evolved here isolated from the rest of the world.

And it was this extreme isolation that made St Helena

the perfect place for the island's most famous human resident.

Napoleon Bonaparte.

The house he stayed in, Longwood House, still stands.

I'm here to meet Joan Thomas who looks after the place.

Napoleon was exiled to Longwood House

after his defeat at Waterloo in 1815.

To be imprisoned on such a tiny island must have been

the worst punishment for a man who hoped to conquer the world.

And his health soon deteriorated.

He died in 1821 after six years imprisoned on the island.

-He actually died in this room.

-Did he really?

And because he died in this room there's nothing original

because the French got very sentimental about the whole thing

and they took everything to France.

He was buried here.

But in 1840 his body was also taken back to France.

Even so, the French flag still flies

at the centre of this remote British territory.

St Helena and Ascension played a key role

in the days of the British Empire.

But the last two overseas territories in my three-year journey

have played vital roles in much more recent military history.

My next stop is on the island of Cyprus in the Mediterranean.

The famous Red Arrows come here to practise

under clear Mediterranean skies.

When Cyprus gained its independence in 1960,

the newest of the UK Overseas Territories came into existence.

Two areas on the island, Akrotiri and Dhekelia,

are still under British control

as the Sovereign Base Areas.

Contained within the Sovereign Base Areas are habitats

that are rare in the Mediterranean.

Like lagoons and marshes that feed exotic-looking birds.

The salt lake at Akrotiri draws greater flamingos...

..just one of 260 species of birds recorded on the Akrotiri Peninsula.

Historical sites are also preserved within the Sovereign Base Areas.

Cliff sides, honeycombed with ancient tombs.

And the ruins of beautifully preserved temples.

There's a wealth of history here.

In just a few minutes,

I can gather handfuls of broken pottery from Roman times onwards.

The island has been strategically important since ancient times.

And it still is.

And that's also true of a tiny spit of land

right at the other end of the Mediterranean.

I've got just one more territory left to visit.

One that's had an even more important role in recent history.

Gibraltar.

It's named after the iconic rock at its heart.

Called the Mountain of Tariq by Moorish settlers in Spain...

Jabal Tariq.

Gibraltar is a tiny overseas territory.

Just six square kilometres.

It was captured from Spain

by a joint Dutch and British force in 1704

and formally ceded to Britain nine years later.

Now, it's home to 30,000 Gibraltarians...

with a proud and unique identity.

DRUMBEAT

Twice a year, the Royal Gibraltar Regiment

re-enact the locking of the city's defensive gates

in the face of the Spanish.

DOG BARKS

The Ceremony of the Keys.

And Britain never gave up Gibraltar.

They saw the Rock as a major strategic location.

Gibraltar played a key role as a supply depot in the days

leading up to Nelson's victory at Trafalgar.

And it proved its worth again during the Second World War.

Gibraltar commands the narrow entrance to the Mediterranean.

Without control of the Rock, there might have been

no North Africa campaign and no vital Second Front in Europe.

So, Churchill ordered the construction

of a vast network of tunnels within the Rock itself,

making an impregnable fortress.

TUNING RADIO

He even built secret chambers which would be manned by a special

top secret team if the Rock fell to German forces.

The tunnels and chambers were lined with cork to deaden sound.

And the mission of the stay-behinds was to sneak through the tunnels

to spy on the Germans.

Secret tunnels and chambers.

It seems more like a scene from a James Bond film.

But if the Rock had fallen...

this would have been reality.

Of all the territories I've visited,

the strategic importance of Gibraltar is the most obvious.

The entrance to the Mediterranean is very narrow.

Africa is clearly visible from the Rock.

There are other African connections here.

Barbary macaques.

A type of monkey that normally lives in the mountains of North Africa.

The monkeys may have been introduced from North Africa

long before the British came here,

but they've made the Rock their home.

The only wild population of monkeys in Europe.

MONKEYS BARK

They're now as iconic as the Rock itself.

They used to be under the care of the British Army

with an officer in charge...

responsible for feeding and maintaining

the most unruly troupe in his regiment.

Today, the local natural history society looks after them.

There was good reason for the Army to attach such importance

to this colony of monkeys.

'An age-old legend is

that if the macaques ever left Gibraltar

the Rock would fall and the British would leave.

Winston Churchill believed in this legend so resolutely that,

during World War II,

as the macaque population levels were falling,

he ordered the military authorities to fly in macaques from Africa

to bolster the local population and boost troop morale.

'It doesn't look like these monkeys have any plans to leave

'their comfortable home just yet.'

It's taken me three years

but I finally made it to every one of the UK's overseas territories.

What I found are the jewels in the crown of the UK's natural heritage.

From an ice-bound wilderness

to tropical wonderlands.

I've seen some of the most impressive wildlife spectacles

on the planet.

I've met some extraordinary people

working to preserve this natural heritage,

to safeguard the real treasure of these treasure islands,

and who have shown me that, with dedication,

we can rescue species from near-extinction.

Their wildlife heritage is an integral part

of the overseas territories,

and nowhere more than on the last place I visited - Gibraltar.

As the legend tells us - if the monkeys leave, the Rock will fall.

'But at the start of the 21st century

perhaps the legend should be reversed.

It's the responsibility of the UK government

to ensure that the macaques

and all of this incredible wealth of wildlife

survives long into the future.