Pardon me having only read the first post of this thread, The Branch Line Between St Helns Cwntral and St Helns Junction (Merseyside) now compleatlly Dissused Still has track as far as Raven Heas Works but you would still have to have permison to access it from St Helns Ctl Station even to go along there on foot as I would Immagine that it is still ownwned by the Railways.

You can wiew it from a footpath crossing by the canal, but last time I looked, it was overgown with vegetation, unsuitable for your purpose, - and not a place you would want to be on your own with expensive equipment.

Theres disused railway line in Birkenhead,on the Wirral,its the old bidstan dock railway.......track and signals are stil there with all the trees and grass.....