In September 1932 the Air Ministry issued Specification B.9/32 for a twin-engine bomber for which both Handley Page and Vickers tendered. Each was awarded a contract and the resulting prototypes, the Handley Page H.P.52 and the Vickers 271, flew within a week of one another, the former on 21st June 1936 and the 271, known later as the Wellington, on 15th June.
Considering they shared the same specification, the two types could hardly have been more different, Handley Page going for an extremely slim fuselage with three manually-operated gun positions, Vickers adopting a portly fuselage with power-operated turrets and manual beam guns.
In spite of an antiquated appearance the Hampden, as the bomber was subsequently named, had several remarkable characteristics. With the use of Handley Page leading-edge slats it was able to land at only 73 mph (117 km/h), while its maximum speed of 254 mph (409 km/h) was higher than that of either the Wellington or the Armstrong Whitworth Whitley, and it could carry 4,000 lb (1814 kg) of bombs for 1,200 miles (1931 km), compared with the Wellington's 4,500 lb (2041 kg) bomb load over the same distance.
Following an order for 180 Hampdens placed on 15th August 1936, to a new Specification B.30/36, the production prototype flew in 1937. Simultaneously with the first contract another was placed for 100 aircraft with Napier Dagger engines, these being produced under the name Hereford. In May 1938 the first production Hampden Mk I aircraft from the Handley Page line was flown at Radlett, and on 24th June the type was christened officially by the Viscountess Hampden.
Build up of the RAF was then in full swing and on 6th August 1938 other orders were placed: English Electric at Preston was contracted to build 75, and in Canada a British mission negotiated for 80 more to be constructed by a consortium named Canadian Associated Aircraft Ltd. These sub-contracted Hampdens began to come off the production lines during 1940.
Following trials at the Aircraft and Armament Experimental Establishment, Martlesham Heath, and at the Central Flying School at Upavon, deliveries to the RAF began in September 1938, with the first batch of Hampdens going to No. 49 Squadron at Scampton, Lincolnshire. No. 49 Squadron was part of No. 5 Group, which eventually was equipped completely with Hampdens. When World War 2 broke out 10 squadrons were using the type: Nos 7 and 76 at Finningley; Nos 44 and 50 at Waddington; Nos 49 and 83 at Scampton; Nos 61 and 144 at Hemswell; with Nos 106 and 185 in reserve.
Early operations in the daylight reconnaissance role were uneventful, but on 29th September the Hampden's shortcomings were highlighted vividly when five out of 11 aircraft in two formations were destroyed by German fighters when within sight of the German coast. Not long after this it was decided to operate in future under cover of darkness, and some leaflet-dropping missions were carried out.
By the winter of 1939-40 the Hampden had found its most useful role as a minelayer. Aircraft from five squadrons sowed mines in German waters on the night of 13th-14th April 1940, just after the German invasion of Norway, and by the end of the year No. 5 Group's Hampden squadrons had flown 1,209 mine-laying sorties and delivered 703 mines, losing 21 aircraft in the operations, the loss rate of less than 1.8 per rent being considered acceptable.
The Norwegian campaign, however, once again showed the Hampden's 'Achilles heel': because of its inadequate defensive armament it suffered heavily at the hands of German fighters when used as a day bomber.
On the night of 25th-26th August 1940, Hampdens and Armstrong Whitworth Whitleys took part in the RAF's first raid on Berlin, and the Hampden continued to support the night bombing offensive until late 1942 when, on the night of 15th-16th September aircraft of the RCAF's No. 408 Squadron attacked Wilhelmshaven in the Hampden's final sorties with Bomber Command.
From April 1942 Hampdens had begun to transfer to Coastal Command for torpedo-bombing operations, the 157 conversions to this role having the designation Hampden TB.Mk 1. The first two squadrons in this role were Nos 144 and 455, the latter an RAAF unit, and detachments from both squadrons went to the northern USSR for convoy protection operations. Thirty-two Hampdens from the two squadrons left Sumburgh in the Shetlands on 4th September 1942, but nine were lost in the crossing, including two which crashed in Norway and one which crashed on landing in the USSR. The squadrons subsequently handed over their Hampdens to the Soviets before leaving for the UK on 23rd October. No. 455 was also the last operational Hampden squadron, based at Sumburgh, and sinking a U-boat on 4th April 1943, before re-equipping with Bristol Beaufighters at the end of the year.
Thus the Hampden passed out of service. In spite of inadequacies it had its good points: among them were pleasant handling characteristics and the excellent view for the pilot. On the debit side accommodation was very cramped, individual crew members being able to change places only with extreme difficulty, which posed great problems in the case of injuries. In all, 1,432 Hampdens were built, 502 of them by Handley Page, 770 by English Electric and 160 in Canada.

Variant:
Hampden Mk II: designation of two aircraft experimentally engined with two 1,100 h.p. (821 kW) Wright
R-1820 Cyclone radials under the company designation H.P.62