The five secret sites where GCHQ monitored German and Soviet intelligence

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4

5

1 Croft Spa, Scarborough

Direction-finding station in North Yorkshire worked to pinpoint signals from ships in the

North Sea

2 Marston Montgomery, Derbyshire

Remote station where staff would listen to multiple radio operators to identify enemy signals

3 Chesterfield Street, Mayfair, London

Georgian block where Soviet army, naval and air force signals were intercepted

4 Ivy Farm, Knockholt, Kent

Staff worked on decoding heavily encrypted German “noise” – sound that does not carry human communications

5 Abbots Cliff House, Capel-le-Ferne, Kent

Cliff-top station where very high frequency signals from Germany were monitored

Croft Spa, Scarborough

Direction-finding station in North Yorkshire worked to pinpoint signals from ships in the North Sea

Marston Montgomery,

Derbyshire

Remote station where staff would listen to multiple radio operators to identify enemy signals

Chesterfield Street,

Mayfair, London

Georgian block where Soviet army, naval and air force signals were intercepted

Ivy Farm, Knockholt, Kent

Staff worked on decoding heavily encrypted German “noise” – sound that does not carry human communications

Abbots Cliff House, Capel-le-Ferne, Kent

Cliff-top station where very high frequency signals from Germany were monitored