The shop initially maintained and repaired the company's existing fleet of thirty six engines, bought in from private makers, twenty seven from Robert Stephenson and Company.
By 1845 some twenty eight engines were built, at which time the L&MR was merged into the Grand Junction, and new building ceased, with the workshop closing in 1847.
An immediate problem was the frequency of broken crank axles on the inside-cylindered 2-2-2 locomotives from a range of manufacturers.
The works produced a new design, either by Buddicom, or his foreman, Alexander Allan, with outside cylinders.
Accordingly, in 1843, the GJR decided to move its operations to Crewe, which was roughly halfway along the route.