"There you are, waiting at a suburban station, waiting for a train back into town. You've got, most probably, a ten minute wait for the train and then a ten minute journey into Edinburgh Waverley. It's not really a massive length of time. But that's YOUR time! You're hovering around the platform anxiously, keeping a constant watch all the other bodies that are streaming towards it, straining to pick out the one dangerous one in the madding crowds.
"Then you see him. Ex-Colleague, aka Bore of Death. Striding purposely down the steps. Your eyes flash all round the platform to see if there are any hugely fat people you can hide behind - has he seen you yet? Then with dawning horror you realise you're screwed - eye contact is made and you're doomed to desultory, banal small talk the whole way until you get into Waverley. Your hands get sweaty, your heart starts thumping, and you desperately search for an escape route."
She then continues with a bloody excellent escape route which is to pretend that your mobile phone is ringing and then to get into an animated conversation with your pretend friend. All the times I used to avoid ex-colleagues or more often than not boring "neighbours" at Kew Gardens (not my old next door neighbours, as they were cool but "neighbours" whose names you don't even know, but they happen to share the same postcode as you), I used the "head in book" escape route or the "I've suddenly forgotten how to get home/get to work and I must study the tube map as though I've never seen it before in my life" route.
Cheers Croila for reminding me of this and of the fact that, like you, I then feel like "the world's most rotten, misanthropic bitch the whole way home".