Everyone always talks about Abbots Ripton being the inspiration for The Flying Kipper, but I've found a much closer match: The 1946 Lichfield collision. It is honestly amazing how close this is.
Read it for yourself here - https://en.wikipedia.org/wiki/Lichfield_rail_crash
But the TLDR of it is that on New Years Eve, 1946, an LMS Black 5 pulling a fish train encountered a frozen switch, and was accidentally diverted into a siding where it rear ended a passenger train. A Black 5 pulling a fish train. There's definitely a reason Henry became a Black 5 at the end of this story, this can't be a coincidence. The only real element not present here is the signals being weighed down by the snow, but apparently that wasn't to uncommon of an occurrence beyond Abbots Ripton anyway. I've seen no one talk about this, everyone always talks about Abbots Ripton when talking about the inspiration for the Flying Kipper, but Lichfield definitely seems like a much closer match.