A 1929 Birkin Bentley has become the most valuable British-built car ever sold at auction.

The 4.5 litre supercharged "Blower" Bentley sold for £5m at Bonhams' Goodwood Festival of Speed sale on June 29.

In doing so the single seater also set a new record for a Bentley at auction, surpassing the £2.8m achieved by a Speed Six Old No 2 in 2004 by 78.6%, or 7.52% pa.

The previous record for a British-made car was the £3.5m achieved for a 1904 Rolls-Royce in 2007.

The vehicle, one of just 54 built, is no stranger to breaking new ground. In 1931, with owner Sir Henry "Tim" Birkin behind the wheel, it set the Brooklands outer circuit lap record with a 137 mph posting.

Bonhams expert Doug Nye said that it was "wonderful to see this iconic car's true value recognised by the world market", before explaining why the vehicle had performed so well at the sale.

"The Birkin single-seater Bentley was, in effect, the Concorde of its time, the fastest car around the high Brooklands bankings. It was driven by a great British hero in Sir Henry Birkin and was the most glamorous racing car of the era."

The world's most valuable Bentley

It was one of seven cars and two motorcycles on sale from the collection of famed watchmaker George Daniels - a 1932 Alfa Romeo 8C-2300 Long Chassis Touring Spider, which Birkin drove in the 1932 Le Mans 24-Hour race, sold for £2.5m.

The auction also featured a 1912 Rolls-Royce 40/50hp "Silver Ghost" Double Pullman Limousine, affectionately known as "The Corgi", which made £4.7m, setting a new world record for a Rolls-Royce in the process, and more than doubling its £2m estimate.

It gained its moniker from Corgi Toys' decision to include it as a model in the Corgi Classics series in the 1960s.

Robert Brooks, Bonhams' chairman, remarked: "These results again prove the value of provenance and rarity, offered for sale in the best possible surroundings."

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