When Lord Rothermere, owner of the Daily Mail, first challenged the British aircraft industry to build a high-speed six-passenger aircraft, it was his ambition to see Britain build 'the fastest commercial aeroplane in Europe, if not the world'. The year was 1934, and Germany led the world in high-speed designs. Lord Rothmere’s challenge was not purely down to patriotic pride in wanting Britain to recapture the title of the ‘fastest civilian aircraft’ - he also wanted to own one for himself.
Bristol Aeroplane Company had been working on a twin-engine monoplane design, designated Bristol Type 135 and it was this that was further developed and adapted to produce what became the Bristol Type 142. Rothermere placed an order for a single Bristol Type 142, along with a 50% deposit, with the balance payable upon the aircraft’s first flight.
The Bristol Type 142, christened ‘Britain First’, had its maiden flight at Filton on 12th April 1935, and the subsequent tests soon proved the aircraft to be much faster than predicted, so much so that it even outstripped all RAF fighters in service at the time. The success of the Bristol Type 142, and its high performance resulted in immediate interest for a military version.
Designated Bristol Type 142M Blenheim, it differed slightly in that the wing was raised to allow a bomb-bay in the lower fuselage and a bomb-aiming station which was provided in the nose. Further military equipment and defensive armaments were also installed whilst there were additional modifications to the tail plane and elevators. The type was ordered ‘off the drawing board’ against Specification 28/35, with an initial contract for 150 aircraft placed in September 1935, whilst in addition to the RAF production, export orders were also received from Finland, Turkey and Yugoslavia. Licenced production was negotiated for Finland and Yugoslavia aircraft.
The first and only prototype (K7033) flew for the first time on 25th June 1936 and by the end of 1936, some 1,568 aircraft were on order and with contract production in the UK being undertaken by AV Roe & Co Ltd at Chadderton and by Rootes Securities Ltd in Speke.
Although arguably obsolescent against the best German fighters of the day, the Bristol Blenheim gave most valuable service on operations in the early part of the Second World War. The type was subsequently developed into the Bristol Type 149 Bolingbroke (Blenheim IV), Bristol Type 152 Beaufort and the Bristol Type 160 Bisley (Blenheim V).
The Bristol Blenheim IF was a long-range night-fighter version, with four x 0.303 forward firing machine guns mounted under the fuselage and around 200 aircraft were converted to this role. A single Blenheim I was converted to a Blenheim II. It was fitted with long-range fuel tanks and had a maximum weight of 14,000 lb, thereby allowing for an increased bomb load to be carried. This aircraft led to the Bristol Type 149 Bolingbroke (Blenheim IV), which was built in the UK and Canada.
Production numbers for the Blenheim I are widely quoted as 1,134 in the UK (634 manufactured by Bristol, 250 by AV Roe & Co Ltd, and 250 by Rootes Securities) plus an additional 45 manufactured under licence in Finland and 16 in Yugoslavia for a grand total of 1,195 aircraft.