I've been to London a few times before. So last year I found some lovely things at Beyond Retro. Including a swim cap with flowers. This year however, nada!
But no fear. Brick Lane has enough other shops to offer with gorgeous and affordable vintage. Just throw yourself in the Sunday crowd and rummage!
This year I also went looking in the Lower Marsh. Prices are a bit steep for my taste. I did find one lovely shop with ok prices (but I would have loved them to be just a bit cheaper). It's What the butler wore. I went home with 2 summery dresses.