Dunwich Dynamo tonight. They're expecting 1400 rides for the 120-mile night ride to the seaside at Dunwich, the biggest ever. Perhaps it can't be described as a cult any more.
It leaves from the Pub on the Park, Hackney, 8pm ish. No more coach spaces back, apparently, so you'll have to be inventive if you want to join on impulse... or you could just come along to watch the Grand Depart.