Douglas is a 0-4-0WT, who currently lives on the Talyllyn Railway, built in 1918 by Andrew Barclay and Co. Ltd. for the Airservice Construction Corps.
From 1921 until 1945 he worked at the RAF railway at Calshot Spit, Southampton. After a period in store at Calshot he was bought in 1949 by Abelson and Co. Ltd. who presented him to the Talyllyn Railway in 1953. After overhaul and alteration from 2ft to 2ft 3in gauge, he entered service in 1954 and was named "Douglas" at the donor's request. Although smaller than the other locos he has performed well and was returned to service in 1995, having been fitted with a new boiler, turned out in his old Air Ministry Works and Buildings livery.