I've seen the opposite happen a couple of years back on an Intercity operator that can be found across the UK...
Train arrived at a major Interchange, where the Train Manager was to be relieved. Anyway, it arrived full of Football Fans going to an away game in this location, and the footy fans had left a huge mess inside the train which smelt like a Brewery and not a nice one! So as it was booked to sit here for a little while, and the relief TM hadn't made an appearance yet, the TM who worked it in, decided to help the cleaners clear up the mess left by the Football Fans.
A few minutes later, the relief TM had appeared, made a quick pre-departure announcement and prepared for departure from this station. Could hear whistles being blown on the platform, and the doors beginning to close. Suddenly there was this announcement...it was made by the TM who worked it in
"EXCUSE ME...TRAIN MANAGER, PLEASE DO NOT DISPATCH THE TRAIN, THE PREVIOUS TM IS STILL ONBOARD. PLEASE DO NOT DISPATCH THE TRAIN, I NEED TO GET OFF!!!"
To no avail. I could hear "2" on the buzzer, and the driver's reply...and sure enough, we started to move! The other TM was absolutely fuming...he'd not only been locked inside the train, he'd left his gear on the bench on the platform, and...he had to be taken at least 20 miles beyond where he was getting off!