ah-ha!. I'm across that. I'm intending to put all the bikes that have to be unloaded en route in the coach - and it looks like this will cover the odd special bikes. If there's room left over then we'll put some Central London-bound bikes in there as well. The van will have London bound bikes only, with those going on to my place furthest from the tail lift. The only problem item is likely to be Ian McS's bike, if he brings one, and if he wants to get out early.
Most of the coach contingent will be going south from Victoria, which makes the natural place to stop somewhere close to Victoria Station, so my worry is people travelling north or east out of London on the train. I don't know if I can squeeze two combined van/coach stops out of the coach company.