Here's a pic (http://www.francisfrith.com/brackley/photos/bridge-street-c1955_b698011/) of Bridge Street looking down the hill which clearly shows the ramp to the bridge over the railway coming out from the station. Once you know where the bridge was, you can see the ramps on both sides of it.
Loved your pics. I'm here fairly recently but am interested in the railway history, in particular. There are still traces if you dig about a bit. Also been to NYM railway too.