Railway historians discover that the `Rocket' in your pocket is a shilling short of a pound

IMMORTALISED IN a thousand images, George Stephenson's Rocket is a symbol of British industrial genius but scientists said yesterday that most drawings of the locomotive - even the illustration on the back of the pounds 5 note - are wrong.

Stephenson, one of the pioneers of steam traction, had become fixated with winning a competition to build the Liverpool and Manchester Railway but despite Rocket's success in 1829 at the Rainhill trials - a series of races with other early engines - the locomotive proved useless for heavy work.

After four accidents, Rocket became obsolete within two years and it was left to Stephenson's son Robert to improve on the design at his Newcastle upon Tyne workshop, where he produced the finished article, named Planet, 11 months and seven prototypes later.

Research by locomotive consultants Dr Michael Bailey and John Glithero shows that the pounds 5, which claims to show the engine in 1829, incorrectly gives it several of Robert Stephenson's enhancements.

A dome, shown on the boiler, was not added until the spring of 1830, when it reduced the amount of water that bubbled into the locomotive's cylinders as steam was generated. A valve, which should been where the dome is drawn, is incorrectly depicted at the back of the locomotive, while the train's driving wheels are incorrectly based on those added in February 1831, which survive to this day. The original wheels, destroyed in one of the locomotive's accidents, were less advanced.

The 12-week study is the first archaeological examination of the 170- year-old Rocket, which is on loan to the National Railway Museum in York. It suggests that locomotive technology advanced faster during the early 1830s than historians had previously thought. "I don't think anyone could have predicted how many changes were made to the locomotive as part of the rapid development of steam technology," said Dr Bailey yesterday.

The study also offers an insight into George Stephenson. His role as potential contractor and supplier to the Liverpool and Manchester line was the reason the directors of the railway forced him to take part in the Rainhill trials with his competitors. His natural arrogance drove him to prove his locomotives were the best.

"In fact, he even surprised himself at Rainhill," said Dr Bailey. "Rocket was designed to do 12mph but its boiler was such an improvement that it topped 24mph twice. Then, as if to say to the rest of the world, `We really are the best' he performed something of a victory roll and reached 35mph."

After a brief spell of passenger train duty on the Liverpool and Manchester line, Rocket was demoted to branch line work. Unable to keep up with rapid advances in technology, Rocket was sold as a second-hand colliery locomotive and withdrawn from service in 1840.