LNER O2 class 2-8-0 no. 3496 near Potters Bar circa 1928. Some useful location addenda from the LNER Encycloedia web forum:
"the two signals, the straight track, with overbridge - this location is what is locally known as Hawkshead, where there was once a signal box of that name, and near the background bridge was where the LNER's Brookmans Park station appeared."
3496 was a Gresley designed loco for the GNR and entered service in February 1924. Withdrawal as BR no. 63941 came in September 1963 at Grantham mpd.
[Mike Morant collection]