I stand ready to be corrected, but believe that the 4F's built by the Midland Railway had the beading on the splashers, whereas those built by the LMS didn't. The Midland engines were also right-hand drive, with the LMS (other than the initial post-Grouping batch) being left hand drive from No
4207 onwards. There were other differences, Ramsbottom (Midland)/Ross (LMS) safety valves, and LMS boiler mountings were lower in height than the Midland ones.Hope this helps,
David Costigan