Thomas Hill 138C
 
The steam locomotives designed by Sentinel's continued to be produced well into the 1950's when that firm turned its attentions to diesel traction.

The Rotherham firm of Thomas  Hill  were  Sentinel agents, and they built up a unique business converting Sentinel Steam locomotives to diesel power.

The standard Sentinel design was, of course, eminently suitable for this, being chain driven, and relatively little in the way of modification was required to the chassis to accommodate a new form of power.

138C was one of these conversions.

The locomotives original identity is not known, but it was rebuilt as a diesel in 1965, and part exchanged for another Sentinel steam locomotive at the  C.E.G.B.  Power  Station  at Wakefield. The locomotive continued to work at Wakefield until rail traffic ceased there in 1981.

The locomotive was privately purchased and  moved to the Middleton Railway in December 1982.

The locomotive is powered by a Rolls Royce C6NFL diesel engine, developing 189 h.p. Drive is by means of a Rolls Royce type CF 10000 torque converter and spiral bevel final drive through duplex roller chains to the four wheels. 138C was vacuum fitted several years ago.

The  locomotive was again withdrawn from service in 1996 for repair and improvements.

In 2007 the owner gifted the locomotive to the Middleton Railway before being purchased in early 2015 by Elsecar Heritage Railway.

The locomotive was named "Elizabeth" on 13 May 2015.