A vintage car can still be considered authentic even following a substantial rebuild where many of its original parts are replaced, an appeal court heard yesterday.

In a landmark case based on a 1930 Speed Six Bentley, judges ruled that a decision to award damages to a buyer because the vehicle had undergone major work since new “could not be relied on”.

American businesswoman Mercedes Brewer bought the £425,000 Bentley from a respected dealer in 2007 believing it to be in its original condition.

But when she discovered it was not she successfully sued for £90,000 in damages despite Stanley Mann, who sold her the valuable model, insisting she was fully aware of its significant restoration prior to purchase.

This week, lawyers appearing for Mr Mann at the Appeal Court argued that selling the model as “a 1930 Bentley Speed Six” did not imply that the vehicle was entirely original. They claimed that the description of the car had no bearing on the completed restoration work or the vehicle’s provenance.

Upholding the appeal, Lord Justice Rix, sitting with Lords Justice Sullivan and Lewison, criticised the outcome of the earlier hearing. The judges ruled: “A Bentley Speed Six would, as it seems to us, be a Bentley Speed Six even if it had spent the whole of its life mouldering in a Maharajah's garage, and disintegrating there into dilapidation, before being rebuilt..”

Mr Mann welcomed the decision claiming that the previous judgement would have had “immense” consequences for the “entire antiques market”.

Speaking outside the Royal Courts of Justice on Wednesday, he said: “The problem with 80-year-old cars like these is that at some stage everything has to be replaced. If you replace the leg on a Sheraton table, it is still a Sheraton table... This is a good day for the historic car business and indeed, had the flawed (earlier) judgment been allowed to stand, the implications for the entire antiques market would have been immense.”

The lengthy battle over the Bentley began when Mrs Brewer, of Oakham, Rutland, bought the car from Mr Mann, of Radlett, Hertfordshire, nearly five years ago.

Launched in the late 1920s, the legendary Speed Six was built during the company's heyday and is regarded as the finest vintage models Bentley has ever produced.

With a six-and-a-half litre engine providing 180 horsepower, the classic British sports car proved to be Bentley's most successful racer winner with two victories at Le Mans in 1929 and 1930.

But during a High Court hearing in October last year, Mrs Brewer claimed that she had been shocked to discover only part of her Bentley’s chassis was original, and that the vehicle’s engine was a “reconstructed” standard 6.5 litre unit dating to 1927.

Ruling on the case then, Judge Anthony Thornton QC said the car had been so heavily worked on it “was no longer capable of being accurately described as a “1930 Bentley Speed Six Car”.”

But the appeal judges criticised his findings saying he had “misunderstood or misinterpreted the evidence of the experts and that he created issues where there were none.”

They added: “We express our regret at this unhappy outcome, but in circumstances where the trial as a whole was undermined by the judge's apparent loss of the necessary objectivity, no other solution has been possible.”

Mr Mann, who has dealt in vintage Bentleys for more than 40 years, has since bought back the Bentley. After completing further restoration work he sold it on again six months ago for £675,000.