Manufactured in 1967, it had previously been registered N6516Y in the United States, before being sold to McAlpine Aviation in 1970. The accident was investigated by the Accidents Investigation Branch. The final report was issued on 26 February 1975. The cause of the accident was found to be that the pilot of the Aztec entered the active runway without permission. Non-standard phraseology by the controller at Luton was found to be a contributory factor. The ground markings and signage at Luton were found to be compliant with the legislation then existing. No stop bars or stop lights were provided, nor were they required by law. The pilots were not informed by radio of each other's movements, so may have been unaware that the runway was being used for departures in both directions. Although the radio installation on the Aztec conformed to legislation then existing, its arrangement was criticised as the passenger/co-pilot could not hear in his headset transmissions made by the pilot. Four recommendations were made; three concerning the operation of Luton Airport and one concerning the radio installation in aircraft.