On the night of 18th/19th September 1939, just days into the Second World War, a Vickers Wellington Mk1a, bearing the serial number L4256, became the first RAF aircraft lost over Wales. The incident marked a series of sombre firsts: it was the inaugural loss for RAF Harwell, No. 75 (New Zealand) Squadron RAF, and the first Royal Air Force aircraft to be downed in Welsh territory.Investigations revealed that the crash occurred, around 07:00 hrs on 19th September 1939. The extended flight time underscores the crew’s struggle to navigate and maintain control during the mission.