The photographs are part of on interest to illustrate lesser known Teesside achievements. Surprisingly there seems to be a number of Great Western Railway, Swindon built, steam locomotives that have DORMAN LONG, MIDDLESBROUGH frames, although many more frames from metal produced closer to Swindon, eg Port Talbot, Wales.
According to the internet this preserved engine No. 4965 Rood Ashton Hall is a hybrid of the original No. 4965 and No. 4983 Albert Hall. The frames seem to be from the original No. 4965, and the boiler from No. 4983.
Photographs and details courtesy of Alan Boardman.