I feel like half of London could be listed here. Everyone knows about the American candy shops around Oxford St. I live in South London and every other shop is a vape shop or mobile phone accessory/repair shop. Not saying they are all fronts but they feel like it.
Lately I've been seeing CBD and vape products get added to the shelves of small local businesses that are otherwise unrelated. Like a small consignment store that specializes in kids clothing (i love that place because I can replace my kids entire wardrobe when they hit a growth spurt for about $100)