WEBVTT
Kind: captions
Language: en

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This remote beach in the
far south-west of England

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was a major target during
the Second World War.

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It was so tactically important

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that the government's
Petroleum Warfare Department

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installed flame throwers
all the way across it

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to try and repel anyone who might try

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to come ashore and
sabotage what's underneath.

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Welcome to Porthcurno in Cornwall.

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Under here was how Britain
talked to the world,

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and to a lesser extent, how it still does.

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- Under the Porthcurno Beach ran
the original telegraph cables

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linking Britain with her Empire.

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What you're looking at is the cable hut

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which was the original
landing point for the cables

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which ran from Porthcurno
all around the world.

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There were 14 cables. The length of the cables
amassed about 186,000 miles.

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The cables were dragged up the beach,

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terminated into old valve terminations
in the cable hut

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and then the message
was relayed underground

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up to the cable station, which is the
building that now houses the museum.

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These cables were fearsomely
expensive to make and to lay

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and the last thing you needed
is some idiot dropping an anchor on them

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or snagging them in their nets.

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The beach has got very deep sand
and it shifts all the time,

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so it's never been used for fishing,

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so you don't have boats
landing here regularly,

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or you didn't in 1870,
so it was a perfect place.

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We also have World War II tunnels.

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Back in 1939, when war was declared,

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we had Britain's premier
communications hub

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in a very prominent white building,

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standing out on top of a cliff
in a sparsely populated area,

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which wasn't the smartest idea.

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So, 15,000 tonnes of granite
was blasted out from the cliff

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and the whole thing was moved underground.

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- A lot of folks think
that when they're sending

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a message to someone in another country,

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it's getting bounced up to
a satellite and back down.

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But, unless you're in a really rural area,

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that is not the case.

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Most comm satellites
in geostationary orbit,

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which means that they are falling
around the earth

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at the exact same rate
that the earth is spinning below them.

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But to make that orbit work,

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they have to be so far away
that it takes half a second

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for a signal to get beamed
up to them and back down.

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The route around the surface of the earth
is much shorter and much faster

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and it doesn't involve
blasting something into orbit.

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Undersea cables do have
their own troubles, though.

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- November 2016, Jersey pretty much
lost all its internet communication

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because a boat dragged
its anchor across the seabed,

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took out three high capacity
cables, leaving just one,

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and Jersey was... not cut off,

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but hugely reduced communications whilst
they set about repairing them.

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When they laid the first cable out to
the Isles of Scilly from Porthcurno,

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it was all well reported in the media

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about how they were
going to get connectivity.

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What wasn't reported was that
they'd actually made the cable too short.

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So what they did was
they got an end of cable,

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connected this dead end-of-cable
up to the landing station

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and went, "Hoorah, it works!"

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when it wasn't working at all

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and then the media took all the photos,
they went away,

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and then they put the problem right.

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So, don't always believe what
you see on film.

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Or YouTube!

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- There are still active telecom cables
under Porthcurno beach,

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although they're fibre-optic these days,
and they don't surface

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at the Telegraph Museum's
old cable hut here.

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They surface at industrial-looking buildings
somewhere further ashore.

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One of those cables, called FLAG,
goes all the way

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from under this beach here to Japan,

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15,000 miles of cable stopping at a dozen
other countries along the way

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and it can carry up to 100 gigabytes
of data every second.

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And it's just one of many that land
somewhere in this part of Britain.

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The fact that there's also
several buildings owned

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by the British Intelligence Services
around here is not a coincidence.

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So the next time you're in a group chat
with people all over the world

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or video calling someone
on another continent,

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just take a moment and remember that

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somewhere near you there is a beach

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with your conversation literally
flashing underneath it.