199 Squadron was formed at Rochford on 1 June 1917 with Royal Aircraft Factory BE.2e biplanes to teach pilots advanced bomber training.
Between February 1943 and June 1943 the squadron was based at RAF Ingham in Lincolnshire training for maritime mine laying over The Wash.
Following training the squadron returned to RAF Lakenheath for marine operations over the English Channel and North Sea.
In July 1943 the squadron commenced mine laying duties using the Stirling and from February 1944 performed supply drops for the Special Operations Executive.
90 Signals Group to operate in the electronic countermeasures role with the Avro Lincoln and de Havilland Mosquito.