'Haycock' was a British programme of high-priority air mail flights undertaken by adapted de Havilland Mosquito photo-reconnaissance aircraft of No. 544 Squadron from the UK to Yalta and Egypt (via San Severo in Italy or Malta) during the 'Argonaut' conference (31 January/20 February 1945).

A similar programme was undertaken by the aircraft of the same squadron at the time of the Potsdam conference in July and August 1945.