I'm trying to put together a trip over to the Edinburgh castle tattoo for my brother and I late in August. I want to spend a few days in London as well doing the tourist attractions and museums and haved a question for anyone living there:

when I was in London many years ago there was an underground flea market going on. I remember it as taking place in the bomb shelter tunnels left over from the blitz era. Does this activity still carry on and is my memory still correct?