The former Rugby to Market Harborough line (or the section leading from Rugby station heading north) was formerly electrified as far as Clifton Mill station - but cut back - as mentioned, to the stub at Butlers Leap bridge:
The line heading north is seen here in c.1966 equipped with OHLE, in-fact two tracks are electrified on the 'to' Market Harborough section of the line, close to the now-removed rail-over-canal bridge:
http://www.rcts.org.uk/features/mysteryphotos/show.htm?img=66-27-18&serial=44&page=2
A spur to Rugby DED (District Electric Depot) now a Colas depot, a line alongside the carriage sidings, and the single return line from Clifton Mill to the down-side of Rugby station over the golf course viaduct was also electrified, but this has mostly been removed after closure. Although at least one road of the Colas depot is still wired to allow electric trains to access the site.