Between 1845 and 1847, the Eastern Counties Railway received a total of 17 express locomotives of the 2-2-2 wheel arrangement, which were numbered 51 to 67. They can be divided into two batches, both of which had a driving wheel diameter of six feet. There were a few derailments in the early days because the profile of the tires was horizontal and not conical.
No. 63A
Locomotive Magazine, January 1907
While the first ten had a 13 ft 8 in wheelbase from the start, the last seven were only built with a 12 ft wheelbase. On the latter, the trailing axle spacing was later increased by two feet and nine inches. Soon they received a larger boiler with a higher pressure and a roof for the cab. 