London-King's Cross comes to mind.
Well Phileas can catch a train to Newcastle there and be Fogg on the Tyne (sorry, couldn't resist).
And there's a permanent location for Platform 9 3/4 too:
http://www.eastcoast.co.uk/global/ne..._march2012.pdf
Now anyone want to have ago at explaining the logic behind the (otherwise very orderly, naturally) Zurich HB? 26 platforms, but the numbers go to 51...