I remember the Court Chester hauled by 50s, this had many problems, from the route being blocked south of Wolverhampton as the wires were down, then the Guard not signing the WCML from Stafford to Nuneaton & then the 'Icing on the Cake' being nearly getting caped at Bedford until a Traincrew was available to take the 50s through to St Pancras. Oh the joys!
Have had loads of changes of itinerary en route but the Court Chester was probably the biggest balls-up. I still remember the riot at Bedford when BR wanted to cape the train and they tried to get the last HST away before transferring passengers could board: with enthusiasts holding several doors open, to the annoyance of the platform staff, we eventually got our way. Given what subsequently happened, I was glad that I didn't hang around to see if the train eventually made it to St P.
Not quite in the league of a catastrophe was the "Deltic Ranger" in February 1978, from Paddington to Paignton with
Ballymoss. The heavy snow caused an early termination at Bristol TM, a request to run back to Paddington via Cheltenham, Birmingham and Oxford was declined and a direct run back (via the Badminton route) mandated. What was a catastrophe was that, when RPPR organised the re-run three weeks later, with
Meld, my ECML train failed, the loco was replaced with a 40 which was then diverted via the Hertford loop, and we eventually reached KX just as the charter should have left Paddington. Fortunately, WR control were very accommodating and passed us down to Plymouth on a service train (the charter had been diverted to Newton Abbot, detach Deltic, then on with a 46 to Par - due to the Paignton line being unavailable due to engineering work). We caught up with the return working from Par, with 46 003, picking up the Deltic from Newton Abbot - so not quite a total disaster!