smoke deflectors were now incorporated into the design.

The final two locomotives were constructed to the modified design of George Ivatt who succeeded both Stanier, following his retirement, and Stanier's immediate successor Charles Fairburn, who unexpectedly died in office. The first, No. 6256 built in 1947, was the last of the class to be built before nationalisation and it was therefore named in honour of its original designer Sir William A. Stanier, F.R.S..