In 1957, Cottesmore became home to aircraft of the V bombers, the UK's strategic nuclear strike force. The squadrons carried out "Quick Reaction Alert" duties using Handley Page Victor and later Avro Vulcan bombers until 1969. When they left, the base was used by 90 Signals Group. Flight Checking, Trials and Evaluation Flight (FCTEF) used 98 Squadron (Canberras) and 115 Squadron (Varsity and Argosy) to provide ILS and radar trials and checking services to RAF airfields around the world. No. 231 Operational Conversion Unit moved into Cottesmore on 19 May 1969 equipped with Canberras, staying until 12 February 1976 when it moved to RAF Marham.