I haven’t seen it for a while but in Uni days you’d definitely get cards through with mobile numbers on advertising such things. This was when pubs closed at 11 and off licenses / supermarkets put shutters up over their booze. Only used it once, took about 2 hours for a slab of Fosters to arrive at a house party which cost about £30, interest in it dwindled very rapidly. probably a bloody good money earner for people doing that back in the day. I also recall the first weed we managed to buy was off a card posted under a windscreen, an eight of cheap hash arrived fairly promptly in that case.