An unidentified GWR 28XX class 2-8-0 inside Caerphilly Works on 27 April 1963. From information in Eric Mountford's excellent book, Caerphilly Works 1901 -1964, the loco pictured would be 2849 one of five locos originally sent Caerphilly for scrapping, but then redirected to Swindon. The locos entered the works for preparation to undertake the trip to Swindon, after the cessation of repair work.
Note the large pile of bench vices, presumably the works was being stripped at the time!

Photo: R.O.Tuck/Rail Archive Stephenson