This was itself based on a second-hand Decauville owned by Royce which he correctly believed he could improve.

Unlike the Royce 10 which had a flat-topped radiator, the Rolls-Royce 10 hp featured one with a triangular top which would appear on all subsequent cars.

[4] Rolls-Royce intended to make 20 of the cars but only 16 were made[4] as it was thought that a twin-cylinder engine was not appropriate for the marque.

Instead, the cars were sold in chassis form for the customer to arrange his own body supplier, with Barker recommended.

Four are believed to survive: the oldest, a 1904 car registered U44, chassis 20154, was sold for £3.2 million (approx £3.6 million after commission and taxes) to a private collector by Bonham's auctioneers in December 2007; AX 148 from 1905, chassis 20162, belongs to the UK Science Museum Collection and is usually on display in the Manchester Museum of Science and Industry; and SU 13 chassis 20165 from 1905 belongs to Bentley Motors.