Frank Whittle was born on June 1 1907, in the Earlsdon district of Coventry, the son of a foreman in a machine tool factory.

When Frank was four his father, a skilful and inventive mechanic who spent Sundays at a drawing board, gave him a toy aeroplane with a clockwork propeller and suspended it from a gas mantle. During the First World War Frank's interest in aeroplanes increased when he saw aircraft being built at the local Standard works, and was excited when an aeroplane force-landed near his home.

In 1916 the family moved to Leamington Spa, where Frank's father had bought the Leamington Valve and Piston Ring Company, which comprised a few lathes and other tools, and a single-cylinder gas engine. Frank became familiar with machine tools and did piece work for his father.

Frank won a scholarship to Leamington College, but when his father's business faltered there was not enough money to keep him there. Instead he spent hours in the local library, learning about steam and gas turbines.

In January 1923, having passed the entrance examination, Whittle reported at RAF Halton as an aircraft apprentice. He lasted only two days; only five feet tall and with a small chest measurement, he failed the medical.

Six months later, after subjecting himself to an intense physical training programme supported by a special diet, he was rejected again. Undeterred, he applied using a different first name, passed the written examination again and was ordered to Cranwell where he was accepted.

In 1926, strongly recommended by his commanding officer, he passed a flying medical and was awarded one of five coveted cadetships at the RAF College. The cadetship meant that he would now train as a pilot. In his second term he went solo in an Avro 504N biplane after eight hours' instruction.

Whittle graduated to Bristol fighters and, after a temporary loss of confidence due to blacking out in a tight loop, developed into something of a daredevil. He was punished for hedge-hopping. But he shone in science subjects and in 1928 wrote a revolutionary thesis entitled Future Developments in Aircraft Design.

THE PAPER discussed the possibilities of rocket propulsion and of gas turbines driving propellers, although it stopped short of proposing the use of the gas turbine for jet propulsion. However, Whittle launched his quest for a power plant capable of providing high speed at very high altitude.

In the summer of 1928 he passed out second and received the Andy Fellowes Memorial Prize for Aeronautical Sciences. He was rated "Exceptional to Above Average" as a pilot on Siskin operational fighters - but red-inked into his logbook were warnings about over confidence, an inclination to perform to the gallery and low flying.

At the end of August 1928, Pilot Officer Whittle joined No 111, an operational fighter squadron equipped with Siskins and based at Hornchurch, and was then posted to the Central Flying School, Wittering, for a flying instructor's course. In his spare time he conceived a gas turbine to produce a propelling jet, rather than driving a propeller. A sympathetic instructor, Flying Officer Pat Johnson, who had been a patent agent in civilian life, arranged an interview with the commandant.

This resulted in an almost immediate call from the Air Ministry and an introduction to Dr A A Griffith at the ministry's South Kensington laboratory. Griffith was already interested in gas turbines for driving propellers, and scorned Whittle's proposals. The Air Ministry informed Whittle that successful development of his scheme was considered impracticable. Whittle nevertheless took out his jet patent, and qualified as a flying instructor.

Pat Johnson, still convinced by Whittle's ideas, set up a meeting at British Thomson-Houston, near Rugby, with the company's chief turbine engineer. While not questioning the validity of Whittle's invention, BTH baulked at the prospect of spending £60,000 on development.

At the end of 1930 Whittle was posted to test floatplanes at the Marine Aircraft Experimental Establishment at Felixstowe. On leave he publicised his jet engine proposal, unsuccessfully. Fortuitously, a friend from Cranwell days, Rolf Dudley-Williams, was based at Felixstowe with a flying-boat squadron, and his efforts on Whittle's behalf soon bore fruit.

In the summer of 1932 Whittle was sent on an engineering course at RAF Henlow. He did so well that, exceptionally in that period, he was permitted to take a two-year engineering course as a member of Peterhouse College, Cambridge, where in 1936 he took a First in the Mechanical Sciences Tripos.

While he was at Cambridge his jet engine patent lapsed; the Air Ministry refused to pay the £5 renewal fee. But in May that year he received an inquiry from Dudley-Williams, who was by then a partner with another former RAF pilot, named Tinling, in General Enterprises Ltd.

The two men undertook to cover the expenses of further patents, to raise money, and to act as Whittle's agents. In the New Year of 1936 an agreement was signed between Dudley-Williams and Tinling, Whittle, the president of the Air Council, and O T Falk & Partners, a firm of City bankers.

A company, Power Jets, was incorporated and Whittle received permission from the Air Ministry to serve as honorary chief engineer and technical consultant for five years, providing there was no conflict with his official duties.

It was as well, because in July, turbo-jet experiments began at Junkers and Heinkel in Germany; at this stage, Whittle's ideas were not subject to the Official Secrets Act. It was a relief when the He 178, after some promise, was scrapped.

Whittle, seeking somewhere to develop his design on modest Power Jets' capital, returned to BTH at Rugby and the company contracted to build a "WU" (Whittle Unit), his first experimental jet engine. At the same time he tried to persuade companies to develop the specialised materials he needed.

First attempts to run Whittle's jet at Rugby in April 1937 produced a series of alarming incidents as it raced out of control and BTH hands bolted for cover. Money was required for further development, but this was scarce, although an Air Ministry contract provided a paltry £1,900.

In 1938 BTH moved the test-bed to its Ladywood works at Lutterworth where, in September, the engine, reconstructed for the third time, was assembled. A further £6,000 of Air Ministry money was pledged and engine tests resumed in December.

WITH THE OUTBREAK of war in September 1939, the project got a further lease of life. The Air Ministry commissioned a more powerful W 2 from Power Jets, and asked the Gloster Aircraft Company for an experimental aeroplane, specified as E 28/39