Cooling Radio Station

This was an incredibly important national strategic installation during the second world war and remained an important national Post Office site until it's closure in 1963. It closure was brought about by obsolescence of fixed point HF telephony by the new satellite communication technology and the emerging fibre optic technologies.

It is not the intention to repeat the excellent work carried out by Frank R Turner as part of his Gravesend at War series or that of  the 2010 English Heritage report: Cooling Radio Station, Hoo Peninsula, Kent. An Archaeological Investigation of a Short-Wave Receiving Station ( details for this excellent report can be found in our 'Publications section'.

The English Heritage report built on the Frank Turner research and provides a detailed technical description, history and archaeological survey. This page instead wishes to address some associated peripheral points to the record.

The MUSA installation became operational in 1942 and was reserved for high level military and government voice traffic between the UK & USA. The GPO feed of the received traffic was to London where it could be routed to authorised extensions within the UK / US military personnel based in the UK and the PM Winston Churchill in the Cabinet War Rooms. Due to the nature of the voice traffic the transmission was scrambled using the AT3 scrambler system (AT&T) which had been broken by the Deutsche Reichspost in late 1941.

There was an urgent need to replace the scrambler and the Bell Labs developed a new system called SIGSALY in which the first production equipment were installed in the US Pentagon and the basement of Selfridges Department Store in London in 1943.



The SIGSALY equipment consisted of 40 racks of equipment weighing 50 tons but transatlantic voice telephony was secure from German Interception. Thus it can be seen that the Cooling Radio Station was part of Churchill's and Roosevelt's essential wartime communication links.

The steps leading up to the Secret Radio Station at Cooling ~ photo 2012



Further details can be found at:

"Y" intercept station.

The Admiralty realised the significance that radio direction finding could play in the maritime sphere in the period leading to war. This enabled it to "piggyback" onto the GPO development at Cooling to include a High Frequency Radio Direction Finding station within the overall complex. The naval "Y" service operated both HF RDF and signal traffic interception for both the German surface fleet and the submarine U-boat fleet. Cracking of the naval Ultra traffic was less than optimum during the period that the Cooling "Y" station operated and indeed ceased when the U-boat high command introduced the 4th rotor to the Enigma machine until the capture of U559 in 1942 provided a key back in. Cooling "Y" intercept station was operational from the start of WW2 until 1941 until enemy air activity forced it's closure and transfer to Lydd on the South Coast.


A board inside Cooling Radio Station ~ a reminder of its commercial use after being abandoned by the MOD