Is it bad form to write 2 diary entries in one day? Possibly. But the network drives in the office have conked out, and it's Friday afternoon, and I have this all ready to go, so what the hell.
London's lost rivers have fascinated me ever since I first read about them, and since I started cycling in London the contours have fascinated me too. Finding a way to visualise these things was what first got me into OSM (via Maperitive), but I never found the time to finish the job to a reasonable standard. So here's a first attempt, see what you think: