No . 90 Squadron RAF No . 90 Squadron RAF ( sometimes written as No . XC Squadron ) is a squadron of the Royal Air Force . History . World War I . No . 90 Squadron was formed as a fighter squadron of the Royal Flying Corps at Shawbury in Shropshire on 8 October 1917 , moving to Shotwick in North Wales on 5 December 1917 . It was equipped with a variety of types , including the Avro 504 , Royal Aircraft Factory F . E . 2 b , together with a number of Sopwith Pup s . The squadron was intended to equip with the new Sopwith Dolphin fighter , amd was intended to become operational in France in the spring of 1918 , but although it received a few Dolphins in July 1918 , it disbanded at Brockworth , Gloucestershire on 3 August 1918 without becoming operational . The squadron reformed on 14 August 1918 at RAF Buckminster , Leicestershire as a Home Defence squadron equipped with Avro 504Ks with the mission of defending the Midlands against German air attack . Flight s of Avro 504s were based at Buckminster , Leadenham and Wittering , but the squadron saw no action , disbanding on 13 June 1919 . World War II . The squadron reformed at RAF Bicester on 15 March 1937 from a flight of 101 Squadron , as a light bomber squadron equipped with Hawker Hind biplanes as its initial equipment . It replaced its Hinds with the more modern Bristol Blenheim twin - engined monoplane from May that year . It replaced its Blenheim Is with Blenheim Mark IVs in early 1939 , and on the outbreak of the Second World War , became a training squadron , training Blenheim crews for the rest of Bomber Command . It disbanded on 4 April 1940 when it merged with No . 35 Squadron to became part of No . 17 OTU . The squadron reformed once more at RAF Watton on 7 May 1941 as Bomber Command ' s first unit equipped with the American Boeing Fortress I four - engined heavy bomber , moving to West Raynham on 15 May . 90 Squadron flew its first operational mission on 8 July 1941 , when three Fortresses set off from RAF Polebrook to attack Wilhelmshaven ( although only two of them actually managed to bomb the target ) . The squadron typically flew small formations of Fortresses in high altitude daylight attacks , taking part in a large scale attack on the German battleship " Gneisenau " at Brest , France on 24 July . Three Fortresses attacked were to attack from , with the objective of drawing German fighters away from 18 Handley Page Hampden s attacking at lower altitudes . A larger force of 79 Vickers Wellington s would attack later , while the fighters were meant to be refuelling . The operation did not work as expected , with 90 Squadron ' s Fortresses being unopposed , with the German defenders concentrating on the Hampdens and Wellingtons , shooting down two and ten respectively . Small scale attacks continued , with four Fortresses attacking the German " Pocket Battleship " Admiral Scheer " at Oslo harbour on 8 September , losing two of their number to German fighters . 90 Squadron flew its final operational mission over northern Europe on 25 September 1941 . In 51 operational sortie s , 25 were abandoned due to faults with the aircraft , with 50 tons of bombs being dropped , of which only about 1 ton hit the intended targets . The Fortress I was unsuitable for the type of very high - altitude operations by small formations on which the RAF used them . Four aircraft were dispatched to Egypt in November ( of which three reached their destination ) for operations in support of the Western Desert Campaign , with the three survivors being merged into a detachment of 220 Squadron in December . The squadron surrendered its remaining Fortresses to 220 Squadron in January 1942 , with the squadron flying a few Blenheims until it disbanded on 14 February 1942 . On 7 November 1942 the Squadron again reformed as a night bomber squadron , part of No . 3 ( Bomber ) Group , at RAF Bottesford . It was to be equipped with the Short Stirling Mk . I , receiving its first Stirling on 1 December and moving to RAF Ridgewell on 29 December 1942 . Its first operational venture were mining sorties in early January 1943 . The months following saw the Stirling Mk . III ( an improved version ) introduced to the Squadron , which , as a three - flight unit was theoretically capable of providing 24 aircraft to the Group ' s Operational Battle Order . The unit ' s resources were thrown into the Battle of the Ruhr and sent to many of the German targets that were most heavily defended , including Berlin . The Squadron suffered considerable losses over an eight - month period and found it difficult to maintain reserves of men and machines . The Stirlings suffered from deficiencies in design , due to restrictions laid down in the original Air Ministry specifications . After suffering heavy proportionate losses by type , their operations were restricted to Special Duties i . e . : Dropping sea mines , low level supply dropping to the Maquis , shorter bombing raids on invasion objectives . The Squadron was active on all these fronts . By June 1944 the Squadron had been declared operational on Lancaster s . The last raid was to Bremen on 22 April 1945 , the squadron flew 4 , 613 operational sorties for Bomber Command during the war and lost 86 aircraft . Postwar . The squadron continued to operate the Lancaster in the post - war Bomber Command until May 1947 when the squadron re - equipped with Lincolns . It carried out regular detachments from Wyton to Egypt and Rhodesia before it disbanded on 1 September 1950 . The squadron reformed postwar at RAF Marham on 4 October 1950 and was equipped with the B - 29 Superfortress known in Great Britain as the Boeing Washington . On 8 January 1953 a Washington from the squadron " WF502 " mysteriously crashed near Llanarmon - yn - Ial in Denbighshire with the loss of all 10 crewmen , it had flown into the ground at night . In November 1953 the squadron began re - equipping with Canberra s . The squadron was disbanded on 1 May 1956 . On 1 January 1957 , the squadron was reformed at RAF Honington as a V - Bomber squadron , receiving Vickers Valiant s from March that year . The squadron started to convert to an in - flight refueling mission in August 1961 , becoming a dedicated tanker unit on 1 April 1962 when it officially lost its bomber role . Structural problems with the Valiant fleet caused by metal fatigue resulted in the RAF ' s Valiant fleet being permanently grounded on 26 January 1965 , the squadron finally disbanding on 16 April 1965 .