Number 42 Squadron was a squadron of the Royal Air Force. It served during the First World War as an army co-operation squadron and during the Second World War in various roles. Between 1992 and 2010, it was the Operational Conversion Unit (OCU) for the Hawker Siddeley Nimrod MR.2, based at RAF Kinloss, Moray, until the Nimrod MR.2's retirement in March 2010. No. 42 Squadron disbanded on 26 May 2011.