The locomotive units had transverse boilers of a type similar to the Yorkshire steam wagon and the Fairlie, where a single central firebox fed extremely short fire-tubes to a smokebox at each side. Like the Yorkshire, these then returned to a central smokebox and chimney. The outside cylinders were rear-mounted and drove only the leading axle, without coupling rods. The locomotive units were dispatched separately to Newton Heath, where their semi-trailers were attached.
Their coaches were semi-trailers, with reversible seats for 48 passengers and electric lighting.[ii] There were also a luggage compartment and a driving compartment for use in reverse. Folding steps were provided at each of the two doors on each side. They were built by Bristol Carriage & Wagon Co..
Hughes designed a further class of railmotors that were then built at Horwich and Newton Heath, in four batches over five years. They were of the "0-4-0T locomotive + semi-trailer type", with conventional locomotive boilers.
No 15, works number 983, was the 1,000th locomotive to be built at Horwich.
All were inherited by the London, Midland and Scottish Railway (LMS) in 1923, who numbered the locomotives 10600-17 and gave the trailers separate numbers in the coaching stock series. These were the only self-propelled vehicles numbered in the LMS locomotive series rather than the coaching stock series. The first was withdrawn in 1927, and only one survived by nationalisation in 1948. That railmotor, LMS No. 10617, was withdrawn in 1948 without being given a British Railways number. None was preserved.
^These were also listed at 10½ inches in some sources.
^The L&YR had experimented with electric lighting with steam locomotive dynamos from 1885 and, under the electrically-minded Hoy, with wheel-driven dynamos on coaches from 1901 to 1905. However Aspinall had rejected these as too expensive and electric lighting would not become standard until 1914. Like many railways, this had only been in reaction to the 1913 Ais Gill accident.