The class D/4 of the Great Indian Peninsula Railway was a 4-6-0 locomotive for passenger and mail service with a driver diameter of 74 inches. Essentially, it was a superheated version of the BESA HP standard design. Compared to this, the boiler pressure had been reduced by 20 psi and the cylinder diameter was increased from 19 to 20.5 inches. To make space for the superheater, roughly half of the tubes were removed in favour of flues. Only six locomotives of this class were built and also used for very long distance mail trains. One of these ran from Calcutta to Howrah and ran 1,349 miles (2,170 km) in 44 1/4 hours.