there is a disused(?) platform next to it. Does anyone have any information about its history?
Looking at a couple of Middleton Press books, the covered loading dock wasn't there in 1913, but there appear to be (from maps in said books) a couple of side loading docks alongside the siding concerned, and an end loading dock on another siding further to the South in the yard, all open to the elements, and all to the London end of where the present derelict dock stands.
From another photo in one of said volumes I think the covered dock (as is today) may have been erected in LSWR days, ie pre 1923, but can't be sure as the image (taken from a distance) is not that clear further back/in the distance.
The side loading and end loading docks (above) must have all been demolished round about the time the present structure was put up, as no trace remains of them. There was, until the present aggregates business took over the yard, an end loading dock further West, on a short siding approximately due South of Woking Junction itself.
During the 1980's there was also an additional steel framed covered structure put up over the same siding that serves the original covered dock. This addition butted up to, but was not attached to the older structure, at the station end, and was somewhat wider than the older structure, in that it stretched over the entire 'roadway' between the siding mentioned, and the next siding to the South (the one with the brake van standing on, in my earlier image), but did not, as far as remember, cover that siding. This structure may have been only there for a few years, and again, by the time the aggregate business was in place, this newer structure had disappeared, but I can't be any more specific date wise.
Attached a segment of a plan (dated from BR days) of the yard area, with the original covered dock (roof line) highlighted with red dots, and the newer, but short lived extension shown by a solid red lined rectangle. Apologies about shaky hand..
Never took any pics of either structure in their entirety, or in close detail (one comes to regret such things), but also a couple of views, one from over on the UP side through the more recent fencing, and one portraying part of the Woking 150 event, and what was (at the time I believe) Slade Green's pride and joy (08600), the view showing part of the newer structure - the best I can do!