Given its origin, the Blenheim could be called "fast and spurious". The aircraft was initially envisaged as a luxury transport and wasn't a part of any military programme.
The often told story of the six-seat executive aircraft built for Lord Rothermere, proprietor of the aviation-supporting Daily Mail, usually misses the vital point. Why did he want a fast executive aircraft? Primarily it was to show the world that Britain could build a civil aircraft at least as good as the Douglas DC-1. Bristol's Type 142 first flew on 12 April 1935. When tested at Martlesham Heath in June it proved to be 80 km/h faster than Britain's latest fighter prototype.
The outcome was the Bristol Type 142M, the most important changes being to provide armament, a bomb aimer's position, internal bomb stowage and more powerful 626kW Mercury VIII radial engines. To make room for a bomb bay in the lower fuselage, the low-wing configuration of the civil Type 142 was changed to mid-wing for the military version, which became named Blenheim.
The requirement for longer range led to evolution of the long-nosed, increased tankage and strengthened landing gear version, named originally Bolingbroke I. These began to enter RAF service in March 1939, by then designated Blenheim IV.
By the outbreak of World War II Blenheim Is had been superseded by Mk IVs in the UK, but remained in first-line service in Greece and the Western Desert. Blenheim IF night-fighters had their armament of two machine-guns supplemented by a four-Browning under-fuselage gun pack. These aircraft pioneered British airborne radar, serving throughout the blitz of 1940-41.
Blenheim IVs had their share of early fame - making the first reconnaissance over Germany of World War II on 3 September 1939, the first attack on the German Fleet on 4 September - and were continuously active over Europe on daylight raids until late 1941.
On 24 February 1941 a modified Blenheim, known originally as the Bisley, made its first flight. Powered by two 708kW Mercury 30 engines, it featured an extensively modified nose and other changes. As the Blenheim V, a total of 940 production aircraft were eventually built in several variants. Although not popular with its crews it remained operational in the Far East until the latter part of 1943.
And a now, three derivatives. First, Bristol 152 Beaufort torpedo bomber (the first prototype flew on October 15, 1938. Entered service in 1940. A total of 1900 aircraft were built, 1200 in Great Britain and 700 in Australia):
Second, the Beaufighter (Bristol 156), painted by Michael Turner:
And third, the ill-fated Bristol 163 Buckingham, ordered as a Blenheim replacement:
We can also mention the Brigand (Bristol 164), a long-range attack aircraft entering service in 1949:
Source: Virtual Aircraft Museum