Neil Williams wrote:

I have never, ever, in many journeys over many years, encountered
anything I'd think to be remotely threatening on a late-night train.
I've seen drunk people, silliness, high spirits and such, but never
anything seriously threatening.

Thankfully rare, but my tally is two incidents - one in the 70's when I
was the target of unwanted attention (and actually found the BTP rather
intimidating as well on that occasion), and the other in the 90's where
I was aboard a train including some Mk1 corridor coaches, and observed a
man walking past my compartment carrying a knife with roughly a six-inch
blade, followed shortly afterwards by two uniformed police officers, who
presumably detained him soon afterwards as the train was delayed at its
next stop for about 10 minutes. Both of these were after midnight.
--
http://gallery120232.fotopic.net/p9632956.html
(43 084 at Basingstoke, May 1995)