When steam railcars appeared in Great Britain in large numbers at the beginning of the century, James Manson of the G&SWR also followed the trend and had one steam railcar built in 1904. The vehicle consisted of a small, four-coupled tank locomotive and a conventional passenger carriage, which had only one bogie at the rear end. In theory the locomotive could have been detached from the carriage and used independently, however its water supplies were carried under the floor of the carriage.

The railcar was built in G&SWR's own workshops in Kilmarnock and was used on the nearby line between Mauchline and Catrine, which was only about three miles long. Two identical vehicles were ordered the following year. The use of the railcars ended in 1916 and in 1922 they were sold to the scrap dealer.