Second post in a week on the nuclear front: according to a timetable published somewhat irresponsibly by Greenpeace a couple of years ago, trains carrying nuclear waste travel via Peckham, Denmark Hill and Lewisham en route from Dungeness to Willesden Junction before heading onwards to Sellafield. From the schedule (PDF), you can catch them passing through these stations around 7pm on Mondays, Wednesdays or Thursdays.
