In William Barton Wright's effort to unify the Lancashire & Yorkshire fleet with a smaller number of locomotive classes, the class 629 was developed as a 4-4-0 express locomotive. The first eight came in 1880 from Sharp, Stewart & Co., where most of the development took place. They had a driving wheel diameter of six feet (1,829 mm), which meant that even topographically demanding lines were no problem. Compared to the previous 2-4-0 locomotives, smaller tenders initially had to be used because the turntables were too short.

Other batches came from Sharp, Kitson and Vulcan. The last 16 were delivered by Vulcan in 1887 under Aspinall, bringing the total to 110. These had a longer wheelbase between the driving axles, a different type of suspension and smaller bogie wheels. All but two of the class 629 locomotives were retired by 1914. These two went first to the LNWR and then to the LMS, where they were decommissioned in 1930. Aspinall used class 629 as the basis for his classes 2 and 3.