This is a nice shot taken from Temple Meads platform of Old Oak Common's pioneer "County" in the form of 1000 "County of Middlesex" complete with her original double chimney, the only "County" so equipped from new.
The fireman is taking a breather and it appears that 1000, with her well filled tender, has just come off the adjacent Bath Road Depot, out of shot on the extreme right, and is waiting to run up to the northern end of Temple Meads in preparation to work a passenger turn back to Paddington.