While the dogs were walking me, I remembered another one about the G&SWR, although by this time it would be the early days of the LMS.
My mother went to Glasgow Uni. She took the train up to Glasgow from Irvine every day. Coming back one evening, she managed to get on the wrong train. I can't remember if it was an Ardrossan train that went "the wrong way" at Kilwinning, or an Ayr train that failed to stop at Irvine, but when she realized what was going on, she panicked and yanked the cord!
She was probably 18 or 19 at the time and grandpa was on pretty good terms with the station master at Irvine, so the whole thing was duly hushed up.