You Are Missing
As some people noted yesterday, Kings Cross - and specifically platform 9 3/4 - is where the Hogwarts Express departs. The best photo opportunity is, of course, with you pushing the "trolley" through the wall. Makes for some fun, anyway, and rather nice to see the station management have a sense of whimsy. There is a nearby bookshop that is capitalising on the merchandising, but (possibly surprisingly) that's all.