This sounds entirely implausible (I happen to know a number of the Inverness-based crew personally) for many reasons. I wonder if such a fantasy has been invented by someone with an axe to grind against CS (for whatever reason), not least because on the one night this year that the Inverness service was cancelled (11th February), the Inverness crew had to travel north on the Lowlander to Glasgow/Edinburgh and by day train back to base, getting back very late (not until 12 noon). There is simply no chance that an incident like that could have occurred in those circumstances. In any case, the Inverness crew that I know are extremely dedicated and professional and would never even conceive of acting in that way while on duty.