The Royal Military College at Sandhurst didn't actually exist until 1819. Before that there was just a temporary Army camp vaguely based in the same area- around Laundry Lane and the mysterious Obelisk. Sandhurst itself was just a sleepy little village on the river, next to a huge forest that was an extension of the Kings Royal Park.
No matter, really...there was an officer's training college a few miles away on the Thames... and if I could remember the name of the town, I would tell you...maybe it'll come to me later today.