When the Liverpool and Manchester Railway was approaching completion, the directors of the company owning it ran a competition to decide whether or not stationary steam engines or locomotives would be used to pull the trains. The Rainhill Trials were arranged as an open contest that would let them see all the locomotive candidates in action, with the choice to follow. Regardless of whether or not locomotives were settled upon, a prize of £500 was offered to the winner of the trial. Three notable figures from the early days of locomotive engineering were selected as judges: John Kennedy, John Rastrick, and Nicholas Wood.
Locomotives that were entered were to be subjected to a variety of tests and conditions. These were amended at various points, but were eventually nailed down to:
Cycloped was the first to drop out of the competition. Built with "legacy technology", it used a horse walking on a drive belt for power, and was withdrawn after an accident caused the horse to burst through the floor of the engine.
Next to go was Perseverance. Damaged en route to the competition, Burstall spent five days repairing it. When it failed to reach the required 10 miles per hour on its first tests the next day, it was withdrawn from the trial. It was granted a £25 consolation prize.
Sans Pareil nearly completed the trials, though at first there was some doubt as to whether it would be allowed to compete as it was three hundred pounds overweight. However, it did eventually complete eight trips before cracking a cylinder. Despite the failure it was purchased by the Liverpool & Manchester, where it served for two years before being leased to the Bolton and Leigh Railway.
The last drop-out was Novelty. In complete contrast to Cycloped it was cutting edge for 1829, lighter and considerably faster than the other locomotives in the competition. It was accordingly the crowd favourite. Reaching a then-astonishing 28 miles per hour on the first day of competition, it later suffered some damage to a boiler pipe which could not be fixed properly on site in the time allotted. Nevertheless it continued its run on the next day, but upon reaching 15 miles per hour the pipe gave way again and damaged the engine severely enough that it had to drop out.
So, the Rocket was the only locomotive to complete the trials. It averaged 12 miles per hour, hauling 13 tons, and was declared the winner of the £500 prize. The Stephensons were accordingly given the contract to produce locomotives for the Liverpool & Manchester Railway.
In a recent (2002) restaging of the Rainhill Trials using exact replica engines, Sans Pareil and Novelty both completed the course, though Novelty needed to be pushed the last few tens of yards. In calculating the speeds and fuel efficiencies, it was found that Rocket would still have won fair and square, since its relatively modern technology made it a much more reliable locomotive than the others. Sans Pareil almost matched it in terms of efficiency, but its firebox design caused it to gradually slow to a halt due to a build up of molten ash (called "clinker") cutting off the air supply. The restaged trials were run over a section of line in Llangollen, Wales, and were the subject of a Horizon documentary, screened by the BBC.