And look at the mental legal stuff on the receipts now, the hoops they have to swing through.
There's got to be a book / film to be made about that place and its history. Maybe not anymore but at some point it constituted a whole alternate economy for that part of London. It's still a bit of a crazy world onto itself.
Not sure if this is true, but a mate told me that was part of (one of many) tax dodges. He also told me that in one of the shops at 12 o'clock everyday, they'd switch to trading as a different enterprise. Apparently a tickertape display above the counter would start up announcing their independence!