The oldest surviving Barclay locomotive in the United Kingdom, Swanscombe was delivered to the Northfleet Coal and Ballast Co., Kent, in 1891. It joined an earlier Barclay and an old Henry Hughes saddle tank, all three eventually being transferred to new quarries and wharves at West Thurrock in Essex. These had been opened in 1912-13, and in 1921 became the property of the Thurrock Chalk and Whiting Company, a subsidiary of Associated Portland Cement Manufacturers, which is now part of the Blue Circle Group

With the increasing loads dealt with on the railway, Swanscombe was unsuitable for the heavier work which involved running from the chalk quarry to a quay on the Thames, heavily graded all the way.  The engines latter years were therefore confined to shunting "Presflo" wagons at the wharves and not used on trips to the firm's chalk quarry.  Swanscombe  received a new boiler in 1929, and a new firebox in 1941.

Swanscombe was purchased by a QRS member in 1965, and initially moved in February 1966 to the LRPS store at Skimpot Lane, Luton.  The locomotive was then moved to Quainton on 18th April 1969 , and later sold to another QRS member.  It was restored and was steamed in 1975 for the BBC TV Play School programme.  After a number of years out of service awaiting heavy maintenance, major work started in 1999, with the locomotive back into service during 2002.

More recently Swanscombe suffered from a failure early in the 2009 season, and there is some concern with some water leaks on the boiler. The necessary repairs have been started, with some work due to be completed at Quainton and the boiler work being sub-contracted out.