Based on the class 8 “Dreadnought”, George Hughes developed a tank locomotive that was also intended for express service. Thanks to the trailing bogie, it now had a 4-6-4T wheel arrangement. The boiler with Belpaire firebox basically resembled the original, but was somewhat lighter. There were no changes to the 75-inch (1,905 mm) diameter driving wheels and the four 16.5-inch (419 mm) diameter cylinders.

Although they had been developed for the Lancashire & Yorkshire Railway, the ten locomotives were directly delivered to the LMS in 1924 and were designated class 5P. They were also known as “Dreadnought Tanks”. However, due to their heavy weight, their possible uses were limited, so that they could only be used between Manchester and Blackpool. A further order for 20 was therefore converted into class 8. The tank locomotives were withdrawn from service between 1938 and 1941.