I saw a good one the other day.
I'm sure it was something like Train A was delayed departing a London station.
This then delayed Train B somewhere on the route, which then delayed Train C on it's journey. But the locations were somewhere like Horsham, Birmingham and Peterborough - really far off ones.
These are more common (and more bizarre) than many people think!
The best I encountered was an incident involving cows on the line at Nailsea and Backwell. By the time the delays had finished spooling across the network, several issues had been caused around Kent and Sussex, including a train from somewhere around Portsmouth to Victoria missing at least one or two stops... basically on the other side of England!
Somebody tried to see if there was any link to a delay shunting something at Bedford, which I don't seem to recall there was, but a good try nonetheless!
In fact, the Coastway routes are particularly notorious for doing this sort of stuff but the other way round; trains from Victoria to the South Coast regularly have to run "fast" to avoid making stops at smaller stations whilst delayed. This is so the sporadic GWR services between Brighton and the random selection of West Country shacks are not delayed.
Some controllers have a bit of a mantra... "Southern must not delay the Pasty Train... Southern must not delay the Pasty Train..."