The 25/30 H.P was the next step up from the Ruston engined 16/20 H.P type and was visually identical except that the bodywork extended all the way to the front of the frame due to having to accommodate the longer 3-cylinder engine (3VSO). This type became the 30DL under the new classification scheme of the early 1940s and it is impossible to tell a 25/30 H.P locomotive from an early 30DL.

A 25/30 H.P. locomotive in the yard at Lincoln. This 1937 shot, which clearly shows the 3VSO engine, was used as a centrepiece in publication 7703 "Economy in Haulage". Note the large 4-pocket couplers, which indicate this is the 4-ton version.