He's the forgotten genius of the British aircraft industry, responsible for some of the most innovative aeroplanes of the pre-Second World War era.

And now the part played by Scots aircraft designer Frank Barnwell in helping Britain set a series of world altitude records in the 1930s has been revealed in a new book, Combat in the Stratosphere.

Born in Lewisham, South London in 1880 but raised in Glasgow from the age of one, Barnwell attended Fettes College in Edinburgh and the University of Glasgow, earning a BSc in naval architecture while serving an apprenticeship at Fairfields shipyard on the Clyde, of which his father Richard was the managing director.

But after spending a year in the US, where’s he said to have met Wilbur and Orville Wright – the first men to make a powered flight – he became attracted to the new field of aviation, and on his return to Scotland abandoned his career in shipbuilding to set up an aircraft engineering firm in Stirlingshire with his elder brother Harold.

At a field in Causewayhead in Stirling on 28 July 1909, he and Harold made history by carrying out the first ever powered flight in Scotland, in a biplane powered by a car engine, designed by Frank and flown by Harold. The aircraft reached a height of 13 feet and travelled some 75 metres across the field before crashing, fortunately without causing serious injury to the pilot.

Two years later the brothers achieved another milestone when they made a flight of over a mile in another self-built aircraft, earning the Barnwells a prize of £50 from the Scottish Aeronautical Society for their achievement.

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Frank’s talents as a designer were recognised by the British and Colonial Aircraft Company – later renamed the Bristol Aeroplane Company – who hired him in 1911. Upon the outbreak of the First World War, he joined the newly formed Royal Flying Corps, rising to the rank of captain and being awarded the Air Force Cross.

His skills as an aircraft designer were considered so important, however, that in 1915 he was recalled home to continue his work at Bristols. Among the aircraft he went on to design was the Bristol F.2, widely considered one of the best fighters of the war. Harold, meanwhile, became a test pilot at the A.V. Roe company, but was killed while testing a new aircraft in 1917.

Remaining at Bristol after the war, Frank became the company’s chief designer, and was responsible for the Blenheim bomber, of which almost 4,500 were produced and which formed the backbone of the RAF’s Bomber Command during the early part of the Second World War.

In the mid-1930s, the Bristol company decided to make an attempt on the world altitude record, and set Barnwell the formidable challenge of designing an experimental aircraft capable of achieving that goal.

His response was the Bristol Type 138, which was built mostly of wood and had an enormous wingspan measuring 66 feet. The Type 138 made its maiden flight on 11 May 1936, with the Bristol company’s chief test pilot Cyril Uwins at the controls.

The attempt on the world altitude record took place on 28 September 1936. As the Type 138 lacked a pressurised cockpit, the pilot, Squadron Leader Francis Swain, wore an experimental pressure suit, which would allow him to breathe in the thin air at extreme altitude.

At 7.30 am, Sqn Ldr Swain took off in the Type 138 from the Royal Aircraft Establishment’s airfield at Farnborough. Afterwards, he described the flight: “I climbed in a series of wide circles and, looking down from about 46,000 feet, I saw London like a little toy town, the Thames and other rivers like narrow ribbons, and the Channel Isles like small stones in a shallow riverbed. At that moment I felt very small and lonely.”

Eventually, he climbed to 49,944 feet, beating the previous record – held by Frenchman Georges Detre – by over 1,200 feet. After a flight lasting around three hours, Sqn Ldr Swain landed safely back at Farnborough. For his extraordinary feat, the pilot was awarded the Air Force Cross.

A further eight altitude records were set using the Bristol Type 138 over the following months. The greatest altitude reached with Barnwell’s aircraft was an astonishing 53,937 feet, which was achieved by Flight Lieutenant M.J. Adam on 30 June 1937.

Tragically, Frank Barnwell was killed in a flying accident on 2 August 1938, at Whitchurch airfield in Bristol, piloting an aircraft he had personally designed. His three sons, John, Richard and David, served in the RAF during the Second World War and were all killed on active duty.

Combat in the Stratosphere is now available to buy in hardback (Air World books, £20).

Visit: www.steventayloronline.co.uk