Sidney Jefferson was one of the very early members of the Watson-Watt team having joined in 1936 from EMI where he had been designing domestic radio receivers. He lived in Bawdsey Manor and worked at Orford Ness. He designed the receivers for the Chain Stations and included novel anti-jamming circuits that later helped counter enemy jamming. He became responsible for the station teams working on receivers, transmitters and test gear. He retained the latter responsibility for most of the war when he was also responsible for the photographic unit. 

He has written several short reports as well as his reminiscences which are included in the Penley Radar Archives (see link below).  He also prepared a booklet for the Purbeck Radar Museum Trust to mark the 50th anniversary of TRE’s move to Worth Matravers in May 1940.