First introduced in 1947, the 94XX pannier tanks were designed by F. W. Hawksworth as a modern version of the 57XX machines of C. B. Collett. The first ten of the 94XX series were built by the Great Western Railway at their Swindon works and were fitted with superheated boilers. On the formation of British Railways in 1948, it was decided to continue building these useful locos, and a further 200 were built by outside contractors between 1949 and 1956. They were not superheated however, as by now this was considered unnecessary for the shunting work on which they were employed.

9466 itself was one of a batch of thirty built by Robert Stephenson and Hawthorn Ltd. under lot No. 383, being delivered to Swindon during February 1952 as RSH works No. 7617. Its first home depot was Worcester and it stayed there until transfer to Bristol (St Phillips Marsh) in January 1961. Towards the end of its working life the engine also saw service from Tondu and Radyr sheds in South Wales, before being condemned for scrap on 6 June 1964 after a working life of only eleven years. 9466 arrived at Quainton in 1975, and has been in the present owner, Dennis Howells' possession since 1977, with the original restoration taking 8 years.

Since restoration, the locomotive has visited and worked as a guest in a number of private lines and railway centres listed below. 9466 is restored and maintained to full Railtrack MT276 main line certification.  It has also worked special steam trains for London Underground, together with Quainton's Met No. 1.

9466 completed its periodic overhaul at Neasden Depot during May 2004, returning to Quainton by the end of that month. During 2006 the locomotive has been fitted with Train Protection and Warning System (TPWS) and On Train Monitoring and Recording (OTMR) systems, now mandatory for mainline operation in the UK.  No. 9466 is the first 0-6-0 tank locomotive to have TPWS and OTMR fitted.  

9466 has visited many preserved railways and other locations in the UK including:

• Battlefield Line (1999, 2000, 2001, 2005)
• Cholsey & Wallingford Railway (1999, 2000)
• Great Western Society, Didcot (2000)
• Gwili Railway (1990)
• Llangollen Railway (2007)
• Mid Norfolk Railway (2006) - The first steam locomotive to operate over this 11 mile long, normally diesel operated route, since 1955.
• Nene Valley Railway (2004, 2005, 2006)
• Old Oak Common Depot Open Days (2000)
• Severn Valley Railway (1999, 2001, 2005)
• Spa Valley Railway (2005, 2006)
• STEAM, Swindon (2005)
• Steam on the Met (1999, 2000)
• West Somerset Railway (1999, 2000, 2001, 2004, 2005)

Full details of the locomotive's visits over the last few years to various locations, its upcoming visits, and the details of its most recent overhaul, may be found on its own website, www.9466.co.uk.

9466 has now been in preservation, with the one owner, for over twice the length of time it was owned by British Rail.  The locomotive is now certified for mainline use, and it is planned to operate it on a number mainline charters in the Birmingham and Stratford-upon-Avon area during autumn 2007 and 2008.