Thanks for the advice so far. Perhaps I should have mentioned that I'm a Palace season ticket holder with lots of painful experience of police cock-ups in crowd control. Last season the Palace vs Brighton match was an evening one and the police literally erected a solid 10ft high fence across the whole width of Holmesdale Road while the match was taking place to stop the opposing fans meeting just outside the stadium. Completely pointless exercise because when I eventually walked round the long way to Norwood Junction I just about got in before the police shepherded all the Brighton fans over to platform 4 for their special.
Now, my problem this season is that I absolutely have to get back to Crayford by about 6.15pm. I intend to try and leave a few minutes before the end in case it's the Palace fans being held (as it often is for some wierd reason). However, knowledge of the timing of any special train might assist in predicting the likely police action. Indeed, if it's due to leave Norwood Junction at around 1715 say then I'd probably decide to walk to Selhurst instead to avoid any issues. But if it's not scheduled until say 1800 then it would appear as though the Brighton fans may be kept in the stadium and I'd not have much to worry about.
So, when would one expect a one-off special to appear in open train times? Could it not appear until the day before, or would it be there now if it was going to run?
Oh, one more little point. There is a regular special put on from Norwood Junction non-stop to London Bridge on normal Palace home match Saturdays. It leaves at around 1715 having come out of Selhurst depot. I don't usually catch it because I prefer to save money by walking from New Cross Gate to New Cross.