The burly Welshman also designed the very sophisticated and innovative Leyland Eight, which should have been a rival for the Rolls-Royce. Launched in 1920, it was doomed to be one of the British motor industry's magnificent failures. Only 14 were built.
But Parry Thomas now has a memorial, in an important new museum in rural Warwickshire. The sole surviving Leyland Eight - a huge two-seater with a 7.2-litre engine - is a star of the Heritage Motor Centre, which opens today and has the world's biggest collection of British cars, 300 of them.
Peter Mitchell, its infectiously enthusiastic managing director, nominates the white Leyland as one of his two favourite exhibits, the other being the 9.7-litre Austin that contested the French Grand Prix at Dieppe in 1908.
'I've driven many cars whose performance is much more explosive than the Austin's,' he says, 'but nothing can match the thrill of driving one-and-a-
half tons of engine at relatively high speeds on tyres about three inches wide and with brakes not much bigger than pennies]'
Visitors may wonder why such famous British marques as Rolls-Royce, Bentley, Jaguar, Aston Martin, Lagonda, Sunbeam, Humber, Hillman, Lotus, Singer and Vauxhall are not represented in a museum that cost pounds 8m to build. The answer is that the pounds 8m came from the Rover Group and the museum concentrates on those manufacturers that were clipped, butchered, rationalised, reorganised, consolidated and boiled down to the current triumvirate of Rover, Land Rover and MG.
Cars kept by the likes of Albion, Thornycroft, Trojan, Wolseley, Austin, Morris, Standard, Triumph and Riley were originally brought together in 1975, under the ill-fated British Leyland Motor Corporation's wing. The present British Motor Industry Heritage Trust, formed in 1983 and strongly supported by the Rover Group, exhibited about a quarter of its vehicles at Syon Park, Middlesex, until the new Heritage centre was built.
The impressive art deco building - focal point of a 65-acre site - also houses an archive containing about five million engineering drawings, miles of film, mountains of photographs and shelf upon shelf of specifications and production records.
'It's the biggest motor industry archive in Britain and probably one of the three biggest in the world, with Daimler-Benz and Ford,' says Mr Mitchell. 'But they can't match our breadth of information, because we cover so many marques.'
The oldest of these is one of two three-wheelers built by Herbert Austin in about 1896, when he was running the Wolseley Sheep Shearing Company's factory in Birmingham. At the other end of the time-scale stands a modern Mini. The gulf between them is bridged by cars ranging from unique breakers of speed records, such as the thigh- high MG that did 254.9mph in 1957, to such mass-produced models as the Austin Seven, Standard Vanguard and Triumph Vitesse.
The cars are complemented by themed exhibits and a Land Rover demonstration track. A small nature reserve occupies land left to nature when the site was part of an RAF base.
'We are aiming to attract at least 40,000 schoolchildren a year, because the motor car and motor industry involve all manner of educational things, from social and economic history to ecology, physics and fashion,' says Mr Mitchell. 'And we must try to appeal to the people who have to be dragged here by husbands, boyfriends and children. We want the unwilling visitors to go home feeling that they've had a good day out.'
The Heritage Motor Centre is at Banbury Road, Gaydon, Warwickshire (0926 641188).