V9977 was an Handley Page Halifax II that had been sent to the Telecommunications Research Establishment (TRE) at RAF Defford to be used as a flying testbed for the H2S radar. On the afternoon of 7 June 1942, one of its Rolls-Royce Merlin engines caught fire and led to the aircraft crashing near the England-Wales border, killing all eleven crew-members. Among the dead was Alan Blumlein of EMI, who was well known as the inventor of stereophonic sound recording and the 405-line television system used in the UK until 1985.