No idea but the track on the right of the picture doesn't seem to have been used for some time, where as the track she is standing in the middle of looks active. (ive surmised thsi from the rust.
Quite the opposite. The running line opposite has clearly recently been relaid, using steel sleepered track (which looks rusty when new), as is belaid by the new ballast. Steel sleepered track is quite a recent development for track renewals in the UK.
As to the precise location, let's deduce a few truths from the picture: Looking at the quality of the track and the sweeping alignment of the curve, it's a main line or primary trunk route. There's no overhead line, so it's on a major line that has never benefitted from electrification. And looking at the type of trees and foliage aong the cutting, I'd think it's somewhere in central England. The cutting has been dug out at a shallow angle, which suggests that the countryside in the area is fairly flat with few major changes in topography that mean that few earthworks were required along the route, as well as suggesting that the type of soil in that area is soft and easy to work. So all in all, I'd think that the line is somewhere in a belt running roughly east to west through Hertfordshire, Bedfordshire and into Gloucestershire.
So at a complete guess, Midland Main line, Chiltern main line or the Worcester to Gloucester line.