The prince, the brother, the £450m and his Rollers

Two of the most famous marques in British motoring history - Rolls-Royce and Bentley - were kept alive in the dying days of Vickers' ownership with the help of a playboy prince and a £450m cash injection from the oil-rich country of Brunei.

According to a new book to be published next week chronicling the eventual sale of the two brands to BMW and Volkswagen of Germany, Prince Jefri of Brunei spent up to £150m a year in the mid-1990s buying specially built Bentley and Rolls-Royce models for his private car collection.

The cars included half a dozen stretched Rolls-Royce Phantom VIs costing £6m each and a model called the Dominator, which featured a turbo-charged Bentley engine and a Range Rover four-wheel drive system and cost £1.5m. Rolls-Royce also produced road-going versions of its Java concept car for which the Prince paid £750,000 apiece.

The cars were bought through one of Prince Jefri's trading companies in London called Goldcrest. Although the orders were handled by a dedicated group of about 100 designers and engineers at the car company's Crewe headquarters, construction was often contracted out to coachbuilding specialists in Italy, the US and elsewhere in the UK such as Mayflower and Pininfarina.

The book, The Kidnap of the Flying Lady, written by Richard Feast and published by Motor Books International, calculates that during the 1994-97 period roughly half the sales income of Rolls-Royce Motor Cars came from Prince Jefri and his brother, the Sultan of Brunei, reputedly the world's richest man. They bought 70-75 cars a year, often paying three or four times the list price of conventional Rolls and Bentley models.

This helped Rolls-Royce Motor Cars to generate a return on sales of 10 per cent, underpinning the business and helping it to finance the development of new models such as the Silver Spirit and the Bentley Arnage, which Vickers was unwilling to fund. "In other words, the foundations of a respectable public group, which was also a prime defence contractor, were dependent on the whims of wealthy princes with insatiable appetites for cars," says the book.

Prince Jefri and his brother also considered buying Rolls-Royce Motor Cars when Vickers put it up for sale in 1997 and, according to the book, even sent a delegation to the company's Crewe headquarters.

In the end the two princes did not bid and the company was sold to VW for £430m. VW kept Bentley and sold the Rolls-Royce marque on to BMW for £40m.