Can't do that, Topcat, but am almost certain for the 15th.
I was going to pre-book an advanced ticket for £8 from Manningtree but would like to be sure of the exact time we're setting off before that. Don't want to be too late/too early. P'raps you'll know after your recon trip.
Oh, and I've also noticed that the start is from Tower Bridge which is a bit easier for me, but if I ended up coming from Manningtree could anyone meet me at Liverpool Street Station to lead me to the start? I'm rubbish in London and I find all those big scary trike-squashing buses slightly perturbing.
I'm thinking of cycling home from Saafend the following day, or cadging a lift from James.