An experimental section of the Signal School and an Admiralty Signal Establishment had existed since 1917, when the task was devolved from
HMS Vernon. It had moved to
Eastney to study
Radar direction finding, with appointments being made there from 30 December 1935, but the apparatus not arriving until 14 July 1936. With the moving of the main signal school to Leydene House the
Admiralty Signal Establishment also moved, in April 1941, and was established in Lythe Hill House,
Haslemere. The Production department had been set up in Whitwell Hatch Hotel at
Haste Hill, Haslemere by the end of May that year, with a small part of the establishment remaining at the old Signal School in Portsmouth. This became independent in August when the main facility moved. Soon after the opening of the main centre of HMS
Mercury, the Experimental Section in Lythe Hill House and the Production and Development Section at Whitwell House were commissioned as HMS
Mercury on 25 August 1941, and opened as an independent command on 27 August. Later developments saw the establishment of laboratories and workshops at
King Edward's School, Witley, valve production going to
Waterlooville and aerial manufacture to
Nutbourne. Trials were carried out at
Tantallon, near
North Berwick. During its time in operation, HMS
Mercury II had two nominated depot ships, FMB
3521 from 27 August 1941 until July 1946, and MFV
1016 from July 1946 until she was sold in May 1947. This HMS
Mercury II remained in operation until mid 1952. The name then passed to the Admiralty Signal and Radar Establishment in
Portsdown, Portsmouth. This base remained HMS
Mercury II until 1969. ==Citations==