Interesting photo; he first aspect of note is that the loco is an "Atlantic" (4-4-2) of probably Marsh design, for the LBSCR. Study of the mixed coaching stock reveals much obsolescence, and differing origins, seeming strange for a train on SR metals. As the loco is devoid of any visible means of identification (i e., engine/shed code number as of BR era), I deduce that this is well before that latter (BR) period. The "reporting number" on the smokebox door probably relates to an excursion rather than a scheduled service, so not much to be drawn from that, and the further confusing factor is the headlamp (disc) code, which in absence of finer knowledge of SR's route codes, otherwise indicates to me a "freight, mineral, or ballast train, stopping at intermediate stations". Clearly this latter is not the case, but if my observations and comments are of interest (or hopefully, of use!) to anyone else, then so much the better.