The older you get, the more likely your memories will be out of date. A very long time ago I visited Camden Town and what I mostly remember from that visit is an old Victorian warehouse that was being converted into flats. Camden Town was very arty back then, the kind of up and coming neighbourhood that young artists move into because they can't afford the nice, safe places. So a few years later, when I began to come up with some characters and a storyline that included young artists, Camden Town seemed to fit.
Fast forward to today. Or, really, to last year, when I brought out that old story and began to write it. I've been in London many times since that visit, but not up to Camden. So I did a lot of research (mostly involving the Google maps street view), and found flats & workspaces for all my characters, and mapped out routes for Bethancourt and Gibbons to walk while interviewing suspects. The only place I hadn't nailed down was the main one, the converted Victorian warehouse. God alone knows where the real one I saw was, or if it even exists anymore.
That bothered me, and as I began to work my way back into the book, re-reading what I'd written and such, I couldn't help but try to nail it down. And somehow, in doing this, it belatedly occurred to me that perhaps part of my problem was that Camden Town had long ago finished gentrifying and the artists had moved elsewhere.
Bingo. They moved to Shoreditch. And Hoxton. And apparently they're in the middle of moving into Haggerston. It's a pity I've never been to that part of London, or that I can't afford to go now. So I've spent all day re-working the setting for my book. It's still not done, but it's as done as it's going to get today.