"Aircraft of the Royal Air Force, 1939-1945- De Havilland Dh.98 Mosquito." The prototype Mosquito NF Mark XV, MP469, the former pressurised Mosquito prototype, at Hatfield, Hertfordshire, after modification by the De Havilland Aircraft Company as a high-altitude night fighter by increasing the wingspan, and by fitting Rolls Royce Merlin 61 engines with four-bladed propellers. AI Mark VIII centimetric radar in a ‘thimble’ nose radome and a ventral gun pack housing four .303in machine guns were also added before the aircraft joined the High Altitude flight at Northolt, Middlesex for operational trials. Later, MP469 was passed to the Aeroplane and Armament Experimental Establishment, and also saw service with the Telecommunications Flying Unit and No. 85 Squadron RAF.