The Warwick was designed to meet Air Ministry specification B.1/35 for a two-engined heavy (by the standards of the day) bomber. It was designed in parallel with the smaller Wellington, both being derived from the Vickers Type 271 design to Specification B.9/32.
B.1/35 was drawn up for a twin-engined heavy bomber in January 1935; it was intended to make use of more powerful engines then being developed and thus be both faster and carry a heavier bombload than the B.3/34 specification which would be met by the Armstrong Whitworth Whitley. By the end of July, the Air Ministry was able to consider eight designs. The Vickers 284 with Hercules engines was placed first and a prototype ordered along with prototypes of the designs by Armstrong Whitworth (AW.39 a developed Whitley) and Handley Page (HP.55). Before the last two had been built they were cancelled - both Handley Page and Armstrong Whitworth preferring to work on the new specifications for medium (P.13/36) and heavy (B.12/36) bombers. Vickers chose to continue but construction was slowed by work on the Wellington, lack of engines and official expectation that the design would be surpassed by later aircraft.
The specification was modified in 1936 for greater fuel and bombload and in 1937 Rolls-Royce Vulture liquid-cooled "X" engines were named as alternative powerplant and adopted in late 1938. In February 1939 it was decided to not proceed beyond the prototypes because of the work required for the Vulture but this was reversed in the following January.
Vickers-Armstrongs completed two prototypes. The first, (serial K8178) powered by the Vultures flew from Brooklands on 13 August 1939. The second prototype (L9704) was originally designed to use Napier Sabre engines, but development of the Sabre was slow, with all production capacity needed for the Hawker Typhoon fighter, so L9704 was instead fitted with the Bristol Centaurus radial engines, flying on 5 April 1940. The Vulture engine, needed for the Avro Manchester, was also unlikely to be available in sufficient numbers for the Warwick, and proved unreliable. While the Centaurus-powered prototype was more promising, the development of the Centaurus was at an early stage and again engines were in short supply. Use of the American Pratt & Whitney Double Wasp radial was proposed. The second prototype was converted to use the R-2800-S14A4-G engines and first flew in this form in July 1941. The Double Wasp installation was inferior to the Centaurus but the aircraft was ordered with the Pratt & Whitney engine.
The Warwick used Barnes Wallis' geodesic airframe construction pioneered in the Wellesley and Wellington. In this system, a network of intersecting structural members made from duralumin were covered by wired-on fabric. The load was distributed amongst the structure, providing great redundancy in the event of damage, at the expense of complexity of construction.
An initial production order for 250 Warwicks, consisting of 150 Double Wasp-powered Mk Is and 100 Centaurus-powered Mk IIs was placed on 28 December 1940. A total of 219 Warwick Mark Is were built, the last 95 with 2,000 horsepower (1,500 kW) R-2800-47 engines.
Warwick Mark I
- Warwick B Mk I — original production bomber, of 150 ordered, only 16 aircraft were built. They were used for a variety of tests.
- Warwick C Mk I or Vickers Type 456 — transport version for BOAC, for use on its Mediterranean and North African routes. 14 built.
- Warwick B/ASR Mk I — 40 aircraft converted from the Warwick B Mk I bomber. The Warwick ASRs were used as air-sea rescue aircraft. They could carry two sets of Lindholme lifesaving equipment.
- Warwick ASR (Stage A) — 10 aircraft converted from the Warwick B Mk I bomber. The Warwick ASR (Stage A) was used for air-sea rescue. They could carry one airborne lifeboat and two sets of Lindholme lifesaving equipment.
- Warwick ASR (Stage B) — 20 aircraft converted from the Warwick B Mk I bomber. The Warwick ASR (Stage B) were air-sea rescue aircraft, carrying the same equipment as the Warwick ASRs and ASR (Stage As).
- Warwick ASR Mk I or Vickers Type 462 was an air-sea rescue version, it could carry an airborne lifeboat. The aircraft was powered by two 1,850 hp (1380 kW) Pratt & Whitney Double Wasp R-2800-S1A4G radial piston engines; 205 built.
Warwick Mark II
- Warwick B Mk II or Vickers Type 413 — bomber prototype, only one example was ever built, converted from a Warwick B Mk I.
- Warwick GR Mk II or Vickers Type 469 — anti-submarine, general reconnaissance version. It was equipped to carry torpedoes and bombs. It was powered two 2,500 hp (1,864 kW) Bristol Centaurus VI radial piston engines; 118 built.
- Warwick GR Mk II Met — meteorological reconnaissance version of the Warwick GR Mk II; 14 built.
Warwick Mark III
- Warwick C Mk III or Vickers Type 460 — transport version. It had a pannier-like extension below the central fuselage, the normal loaded weight being raised to 45,000 lb (20,400 kg). It could carry 24 equipped troops or eight to 10 passengers in the VIP version. No armament was carried; 100 built.
Warwick Mark V
- Warwick GR Mk V or Vickers Type 474 — anti-submarine, general reconnaissance aircraft. It was powered by two Bristol Centaurus VII radial piston engines, armed with 7 machine guns and could carry 6,000 pounds (2,700 kg) of bombs, mines or depth-charges. A Leigh light was fitted ventrally. The first operational sortie was carried out by 179 Squadron on 4 December 1944; 210 built.
Warwick Mark VI
- Warwick ASR Mk VI or Vickers Type 485 — final air-sea rescue version. The aircraft was powered by two Pratt & Whitney R-2800-2SBG Double Wasp radial piston engines; 94 built.