Boulton Paul Bourges The Boulton & Paul P . 7 Bourges was a prototype British twin - engined biplane day bomber built by Boulton & Paul to replace the Airco DH . 10 . Despite demonstrating excellent performance and manoeuvrability , only three prototypes were built , post World War I cost cutting leading to the DH . 10 not being replaced . Development and design . In 1918 , the British Air Ministry drew up specification A . 2 ( B ) for the replacement of the Airco DH . 10 medium bomber , despite the fact that the DH . 10 Amiens had not yet entered service . In response , J . D North , chief designer of Boulton & Paul ' s aircraft department designed a twin - engined aircraft , the P . 7 Bourges , powered , like most of the types designed to replace the DH . 10 , by two of the new ABC Dragonfly radial engines . The ABC was ordered off the drawing board by the Ministry and high hopes were held for it . The Bourges was a three - seat , three bay biplane with unstaggered wings of all - wooden construction . The armament was two Lewis gun s - one in the nose on a Scarrf mounting and the other in the dorsal position - and 900 lb of bombs in three bomb cells with doors . Three prototypes were ordered by the Air Ministry . Delays in delivery of airworthy examples of the Dragonfly lead to the decision to fit the first prototype with the much less powerful ( 230 hp / 172 kW ) , but reliable Bentley BR2 rotary engine as a temporary measure , allowing a first flight as the Bourges Mk IIA in June 1919 . Frank Courtney demonstrated the Bourges at Hendon at the end of May 1919 for a reception for Commander Read who had led the crossing of the Atlantic by US seaplanes . The magazine " Flight " commenting on its aerobatic capabilities and general performance though having already flown about 3 , 500 miles . It was fitted with Dragonflys in July , becoming the Bourges Mk IA . Both the Bentley and ABC engined Bourges demonstrated excellent performance and manoeuvrability , being able to be looped and rolled with ease . Courtney wrote that it could " be thrown around in loops , spins , rolls . . . without any special effort " . This acrobatic quality was displayed for the reception at Hendon of Commander Read after his cross - Atlantic crossing by flying boat . The second aircraft was fitted with a gulled upper wing to improve the field of fire for its gunners - the engines moved down to the top of the lower wing . To give greater clearance for the propellors , the undercarriage was lengthened . Fitted with Dragonflys , it was designated the Bourges Mk IB . It would crash in 1919 and its structure reused for a different project . The third Bourges was also originally built as a Mk IB , but when Boulton Paul realised that the reliability problems with the Dragonfly could not be cured , it was refitted with BR2s , being redesignated Bourges Mk IIB . In 1920 - 21 the third prototype , the Bourges P . 7B " F2905 " was again re - engined , this time with 450 hp ( 336 kW ) Napier Lion engines fitted onto the lower wing , and was flown both with the original straight upper wing ( Bourges Mk IIIA ) and with the gulled wing ( Bourges Mk IIIB ) . While , in this form , it was superior to the other types planned as DH . 10 replacements , the RAF had by this time abandoned the requirement , and the Bourges was used for extensive testing at the Royal Aircraft Establishment , Farnborough continuing in use until 1924 . On one occasion it was used at a public display at Croydon in a mock dogfight with two Nieuport Nighthawk fighters . The second prototype was rebuilt to produce the Boulton Paul Atlantic .