Thank you for sharing all this information and actual coach numbers.
Just to clarify the movement of coaches UP & Dwn the Branch.
Each day, Mon - Sat, two sets of stock were used. Each, Composite & Brake Second, 1948 to 1957.
They were all stored overnight at Highbridge Station, the total number of set, I do not know, but I think it might have been as many as 4.
Set 1 plus Set 2 (ECS) left Highbridge at about 7:00 am to Evercreech Junction, were they were split. (not many photos of this double set can be found).
Set 1 would return to Highbridge at 8:15 am
Set 2 would return to Highbridge at 9:55 am
They would then both run up and down the line for another two runs each way.
Set 1 would return finally at 19:03
Set 2 would return finally at 22:12
Times changed slightly with the alteration of the WTT and varied SX & SO, but remained fairly constant.
After 1957 Set 1 would make the first run of the day from Highbridge - Evercreech Junction - Highbridge on its own and would pick up Set 2 (ECS) for the 9:45 run back the Evercreech. Hence the photos that you see on the line, after that time, show a double set of stock with the ubiquitous van sandwiched in between and on the end, allocated to that turn.
I've never seen a photo of a double set coming back to Highbridge.
However I am yet to come across a photo of two GWR 'B' set running together, or to that matter 'B' set with a van!
I trust this is of help.
Should there be anymore information or errors in what I've posted I'd be pleased to know.