Doing a bit of poking around on...

...Flickr yesterday night, I noticed a bunch of people had photos of a bit of wall that is quite obviously from Kings Cross station (same dirty brick work anyway), and is clearly labelled with a large sign saying "Platform 9 3/4"! It looks like it might be on a bit of wall *before* you actually get to platforms 9 and 10 (so not *really* what JKR describes, which I got a shot of the other day, but nice of British Rail to put up this tribute, none the less)...

I'll go and try to get a snap later... ;)