This remote beach in the far south-west of England
was a major target during the Second World War.
It was so tactically important
that the government's Petroleum Warfare Department
installed flame throwers all the way across it
to try and repel anyone who might try
to come ashore and sabotage what's underneath.
Welcome to Porthcurno in Cornwall.
Under here was how Britain talked to the world,
and to a lesser extent, how it still does.
- Under the Porthcurno Beach ran the original telegraph cables
linking Britain with her Empire.
What you're looking at is the cable hut
which was the original landing point for the cables
which ran from Porthcurno all around the world.
There were 14 cables. The length of the cables amassed about 186,000 miles.
The cables were dragged up the beach,
terminated into old valve terminations in the cable hut
and then the message was relayed underground
up to the cable station, which is the building that now houses the museum.
These cables were fearsomely expensive to make and to lay
and the last thing you needed is some idiot dropping an anchor on them
or snagging them in their nets.
The beach has got very deep sand and it shifts all the time,
so it's never been used for fishing,
so you don't have boats landing here regularly,
or you didn't in 1870, so it was a perfect place.
We also have World War II tunnels.
Back in 1939, when war was declared,
we had Britain's premier communications hub
in a very prominent white building,
standing out on top of a cliff in a sparsely populated area,
which wasn't the smartest idea.
So, 15,000 tonnes of granite was blasted out from the cliff
and the whole thing was moved underground.
- A lot of folks think that when they're sending
a message to someone in another country,
it's getting bounced up to a satellite and back down.
But, unless you're in a really rural area,
that is not the case.
Most comm satellites in geostationary orbit,
which means that they are falling around the earth
at the exact same rate that the earth is spinning below them.
But to make that orbit work,
they have to be so far away that it takes half a second
for a signal to get beamed up to them and back down.
The route around the surface of the earth is much shorter and much faster
and it doesn't involve blasting something into orbit.
Undersea cables do have their own troubles, though.
- November 2016, Jersey pretty much lost all its internet communication
because a boat dragged its anchor across the seabed,
took out three high capacity cables, leaving just one,
and Jersey was... not cut off,
but hugely reduced communications whilst they set about repairing them.
When they laid the first cable out to the Isles of Scilly from Porthcurno,
it was all well reported in the media
about how they were going to get connectivity.
What wasn't reported was that they'd actually made the cable too short.
So what they did was they got an end of cable,
connected this dead end-of-cable up to the landing station
and went, "Hoorah, it works!"
when it wasn't working at all
and then the media took all the photos, they went away,
and then they put the problem right.
So, don't always believe what you see on film.
Or YouTube!
- There are still active telecom cables under Porthcurno beach,
although they're fibre-optic these days, and they don't surface
at the Telegraph Museum's old cable hut here.
They surface at industrial-looking buildings somewhere further ashore.
One of those cables, called FLAG, goes all the way
from under this beach here to Japan,
15,000 miles of cable stopping at a dozen other countries along the way
and it can carry up to 100 gigabytes of data every second.
And it's just one of many that land somewhere in this part of Britain.
The fact that there's also several buildings owned
by the British Intelligence Services around here is not a coincidence.
So the next time you're in a group chat with people all over the world
or video calling someone on another continent,
just take a moment and remember that
somewhere near you there is a beach
with your conversation literally flashing underneath it.