This engine was supplied to the Southall Gas, Light and Coke Company (formerly the Brentford Gas Co.); becoming their No. 4 at Southall gas works. She was delivered in green livery with black lining and white edges, reverting to all green by July 1948. Ownership passed to the North Thames Gas Board on 1st May 1959, still numbered No. 4. By this time the livery was believed to be light green.

In 1964 No. 4 became redundant as new gas production processes were introduce, and the locomotive was withdrawn and put into store. She was purchased by a Quainton Railway Society member in April 1966. Initially she was stored at the London Railway Preservation Society depot at Skimpot Lane, Luton, Beds. No. 4 was then moved to Quainton on the 17th April 1969. AB 1865 was christened Alexander by its new owner.

Alexander left for Fleetwood Locomotive Centre, Wyre Dock Lancashire, in late 1986. A local move to the Southport Railway Centre followed in April 1993, with Alexander returning to steam in July 1994. Soon after restoration she appeared at the Woodvale International Rally between 6th and 7th August 1994 in unlined green livery.

A move to GEC Alstrom, Preston, Lancashire followed on 16th September 1995, following on shortly afterwards to the Borough of Preston Docks, where No. 1865 stayed until July 1996. A loan to the GW Preservation Group at Southall MPD followed between February and June 1997. When the Southall site closed Alexander moved to the East Anglian Railway Museum, Chapple and Wakes Colne, until its boiler certificate expired. No. 1865 is now awaiting maintenance at the Ribble Steam Railway, Preston, arriving there in July 2002.

Current Location - Ribble Steam Railway, Preston