As with the Merchant Navy class, they were fitted with a new design of cab front spectacle plates from mid–1947 due to poor forward visibility. The small windows on the front face of the cab were redesigned to an angled profile, giving improved visibility to the driver. This was a feature fitted to all Bulleid-designed locomotives post-nationalisation. They were introduced in Britain in 1934 with the Gresley-designed "Cock o' the North". Over the next decade the revised design was fitted to existing members of the class. Another modification was the reduction of boiler pressure to to reduce maintenance costs.