7mm version built by Chris Wesson - the 4mm kit builds up to produce a similar model

Valve guides:  Nos. 4771-75 were fitted with a different design of front valve guide to the rest of the class.

Fall plate: The original arrangement was for a fixed extension to the cab platform to suit the fall plate, which was hinged on the tender front plate. Starting with No. 4889 (built August 1941) the fall plate was transferred to the cab platform and a wooden platform was provided at the front of the tender for the fall plate to rest on. The existing engines were brought into line as they passed through shops.

Cylinder wrappers: A circular access cover in the cylinder wrapper was fitted to all but the earliest engines.

Chimney: original type and double chimney with Kylchap cowls fitted to 60858/62/80/81, 60902/03 between October 1960 and November 1961.

Pony Truck: The engines were built with pony trucks incorporating Gresley’s patent double swing link suspension. Starting with No. 884 (4855) in December 1946 the pony truck was replaced with a new design using spring side control. The whole class was fitted with new pony trucks by April 1952.

Frame guard irons: The new pony trucks were longer necessitating the removal of the frame guard irons and the clipping of the cylinder drain cock pipes to the front steps.

Lamp iron - smoke box door: two different types.

New cylinders and outside steam pipes: Between May 1956 and March 1962 71 engines had the original monoblock cylinder casting replaced with three separate cylinders and outside steam pipes.