But possibly the least used sections of catenary are the north facing bay platforms at Lancaster. Presumably intended for electrification to Barrow and Windermere that never happened
I read somewhere
* that BR's original Weaver Jn - Scotland electrification plan included electrification of the Morecambe branch.
Obviously that bit was never authorised (neither was the Morecambe - Heysham line included in the Preston PSB resignalling scheme). But it might partly explain how the north-facing bays at Lancaster came to be wired.
Having said that, back in the days of loco-hauled trains - before DVTs and fixed formations, when you might have found more "stray" locos wandering around the system - I recall on one occasion seeing an electric loco parked (pan down) in one of the bays at Lancaster. It's true the plat. 1 & 2 OHLE has probably not seen any use for a good number of years now though.
The same thing could happen very rarely at other random locations where there were never any regular electrically-hauled services - such as Platform 2 at Wigan NW and the north-facing stub at Warrington BQ. Presumably failed locos taken off trains, or involved in some unusual activity like traction swaps in connection with engineering diversions etc.
* O.S. Nock's book
Electric Euston to Glasgow.