This locomotive is an unusual Andrew Barclay engine in that it is a 0-4-2ST. It was built with 15in x 22in outside cylinders, 3ft 6in diameter wheels and weighed 33 tons 10cwt.
As No.6, it was completed in January 1919 and delivered to the Lothian Coal Co Ltd, Lady Victoria Colliery, Newtongrange, Midlothian, which is now the Scottish Mining Museum. There were four of these 0-4-2STs there, two by Barclay and two by the other Kilmarnock engine builders Grant Ritchie & Co, one of which is also preserved at Prestongrange Mining Museum, Prestonpans, East Lothian.
On the nationalisation of the coal industry in January 1947 it became a National Coal Board (NCB) locomotive based at Lady Victoria Colliery.
About 1958 it was sent to the nearby Newbattle Central Workshops for overhaul, returning around July 1960. In around May 1969 it was moved back to Newbattle Central Workshops for storage. Here its trailing truck was removed and it was bought in this state and moved to Marley Hill on the Tanfield Railway in November 1977.
The locomotive is based on the Tanfield Railway but remains unrestored.