I was travelling from Manchester to Chester via Northwich many years ago, my train, (a 108 Derby lightweight) failed at Northwich.
In those days, Northwich still had its depot & a Cl 40 was duly summoned to drop on top of the 108 & take us all shacks to Chester!
One other noteable working I can recall was having a HST from Crewe to Shrewsbury. This was sometime in the early 1990's & the midlands had had a lot of snow dumped onto it that day. Birmingham was particulaly badly affected & cross country services were being diverted via the marches, (which was relatively unaffected).
I recall in the early 1980's, there was a relief service from Llandudno to London Euston one day. A Cl 24 brought the train down to Crewe for a loco change, only no electric was available. The 24 took the ensemble all the way to Euston - much to the amazement of all concerned.

Would love to have been on that one!