For what it is worth the HMRS LSWR Livery Register says:
Goods locomotives 1883-1922, and secondary passenger locomotives 1883-7
This scheme, developed by Adams in 1883, appears to have continued in use until the grouping with such little modification that it needs to be considered as a continuous topic.
The main colour has been variously described as:-
Dark green; Dark bronze green; Holly green; Dark holly green; Black or very dark green; Very dark green, almost black; Very dark green.
The lining colour was noted as:-
Bright green; Light green; Moderate yellowish green,
As originally specified, the boiler, main frames (below the platform), safety valve lever, outside cylinders, valances, footsteps, wheel centres, tender frames, hornplates, springs, hangers, outside cranks, coal coping and the front of axleboxes were painted dark green. Bogie frames and tender axleboxes were black, and guard irons, buffer sockets and buffer beams were vermilion. Lining was carried out on the boiler bands, cab panels, splashers, sand boxes, cylinder clothing, footsteps and tender sides and end, all of which were edged in black and lined in light green. The edge of the coal coping was black, unlined. No lettering was carried at first, the engine number was marked by cut-out brass figures on the cab side, with the usual presentation on the buffer beams. Other, later, details of lettering and shape of lining conformed to contemporary passenger- engine practice. Long before Urie's time, the guard irons, and probably the frames too had become black.
Cab interiors were buff and the frame interiors (with the motion plate) were probably tan. Toolboxes on the engine platform (e.g. on Beattie 2-4-0Ts) were painted as for tanks. The following parts of engines were painted black:-
cab roof exterior, splasher and tank tops, tank ends, outside motion plate, outside cylinder ends, step treads, guard irons, axles, axle ends, tyres, tender interior, coal rails, hornplates, axleboxes, springs, spring hangers, brake gear, toolboxes on tender platforms and top. As before, buffer beams were vermilion and motion, buffer heads and handrails bright. Builders' plates were retained, but no coats of arms were carried.
Unfortunately the contentious matter of the runningplate (or whatever it should be called) is not mentioned in any of the livery descriptions, but photographs seem to confirm that the logical black was used. Also there are some contradictions in the above, perhaps due to different observers (note the range of colours named), the passage of time, or the practices of different sheds. There does not appear to be any reference to the lining actually being omitted, and it is very difficult to spot it in photographs, especially when covered in even the lightest coat of grime.