It was originally used by the Air Service Constructional Corps (RAF) then was bought in 1949 by Abelson & Co. (Engineers) Ltd. who then sold it to the Talyllyn Railway in 1953.

[2] From October 1921 onwards Douglas spent most of its working life at RAF Calshot near Southampton.

[3] After presentation in 1953 the locomotive was retubed and converted from 2ft gauge at Griffin Foundry, Oldbury (with the conversion being paid for by Abelson) before being taken by road to Tywyn.

[5] Although smaller than the other locomotives on the Talyllyn Railway, it has performed well and was returned to service in 1995, with a new boiler fitted, and turned out in its old Air Ministry Works & Buildings livery.

In more recent years Douglas has been painted in standard Talyllyn Railway livery of deep bronze green lined with black borders and yellow lining; however as of 2010 it was painted red, acting as Duncan from the fictional Skarloey Railway.