The Westland Welkin was a British twin-engine heavy fighter from the Westland Aircraft Company, designed to fight at extremely high altitudes, in the stratosphere; the word welkin meaning "the vault of heaven" or the upper atmosphere. First conceived in 1940, it was built from 1942–43 in response to the arrival of modified Junkers Ju 86P bombers flying reconnaissance missions that suggested the Luftwaffe might attempt to re-open the bombing of England from high altitude.