So that's what it was.
I was too far away to see what was being advertised and it had gone by the time I got back to central London. Splendid idea. I hope we see more.
The regulatory position in the UK?
Too many and too strict in the view of some, but Brits love rules so the position is unlikely to change.
FL
PS: Watch out for bombs on your next visit to the big city. London can be a dangerous place.