Ten tank locomotives, designed by G.W. Reid, were built for the NGR by Neilson, Reid and Company in 1902. It was the first known locomotive in the world to be designed and built as a Baltic type. Known as the Neilson, Reid locomotives until they were designated the NGR's Class F, they were larger versions of the rebuilt Class H locomotive of 1896 and many of the main dimensions were identical. It had a plate frame, Stephenson valve gear and used saturated steam. In 1912 they became the Class E on the SAR.