The King Arthurs were originally designed by Robert Urie as N15s under the London and South Western Railway. They were built between 1919 and 1926 and designed to haul heavy express trains.
They became part of Southern Railway and the Publicity Department gave the class, names associated with the Arthurian Legend of the Knights of the Round Table. Hence becoming known as King Arthur class. Richard Maunsell modified the locos and increased their numbers to 74.
The new locos were built at Eastleigh or Glasgow and the became known as Eastleigh Arthurs or Scotch Arthurs. Sir Lamiel, named after a Welsh Knight was built in June 1925 as a Scotch Arthur by the North British Locomotive Company in Glasgow and was withdrawn from service in October 1961.
777 was originally allocated to Nine Elms shed and was later allocated to Battersea, Bournemouth, Dover, Feltham and Basingstoke. On withdrawal in 1961, Sir Lamiel was stored at Fratton, Stratford and Ashford.
After withdrawal in 1961, Sir Lamiel became part of the National Collection, which later formed the National Railway Museum. The locomotive was stored in various locations before entering the custodianship of 5305LA in 1978 (then based in Hull at Dairycotes as the Humberside Locomotive Preservation Group).
777 returned to steam and mainline condition on 21st February 1982 in Maunsell green livery. The first maineline trip in preservation was over the Settle and Carlisle line on 27th March 1982. Following this, 777 has had a varied and successful mainline career. This included starring in the film “The Cruel Train” and two visits though carriage cleaning plants with loco crew aboard.
The HLPG completed major overhaul of 777 in 1989, then in 1995, 777 moved to the Great Central Railway. She was withdrawn from service again in 1996 for another overhaul.
The 5305 Locomotive Association, the successor to the HPLG, then undertook yet another major restoration and overhaul of 777 returning it to traffic in 2006. Following further mainline and preserved railway work the engine was withdrawn for overhaul in 2017 and stored in the loco shed at Loughborough.