Just after Frederick William Hawksworth had become Chief Mechanical Engineer of the GWR in 1941, he developed a modernized version of the Hall class. This had been designed by Collett in the twenties and still had much in common with older classes. The new locomotive had plate frames which were cast in one piece, but separate cylinders. Also the bogie was built with plate frames. The main dimensions were similar, but Hawksworth used a larger superheater to address the declining quality of coal. Another change was the modified regulator header.

When the first locomotive was delivered in 1944, it received the number 6959, after the last locomotive of the original Hall class was 6958. Originally they carried no names, but they were later named after English and Welsh country houses. More orders followed even after the founding of British Railways. In 1950, No. 7929 was the last one of 71 locomotives. The last 14 were only withdrawn in 1965 when steam traction generally ended in the Western Region. Six were preserved, of which five ran in preservation.