We're coming over the hill.

So it is a bit in Congress in the middle of the

rolling countryside of North Yorkshire next to a caravan park

and a little farm is this grey big building, barbed wire all

round it and lots of strain shaped aerials on it.

Quite a bit of security and a sign saying,

welcome to G. KQ Scarborough.

Here we are. Thank you very much.

Hello. Good morning. Hopefully you're expecting us.

I hope so. Okay, phone's going off.

Any locker with a key.

In a corner of Northeast England, not that far from the beach,

sits the longest continually running listening station in the world.

It's part of G.C.Q, government communications headquarters, an organization which has shaped history whilst keeping its own secrets.

This is the BBC World Service.

I'm Gordon Carrera, and this is the secret history of G. C. H. Q.

Bletchley Park may be the Intelligence Agency's most famous home,

but I'm going to be visiting some of the less well-known sites,

and talking to people who worked on the front lines.

These were people doing painstaking work at times of incredible tension.

First stop, Scarborough, a listening post which dates back more than a century and

also played a role in the most dangerous crisis of the Cold War.

...