1) Did pay phones take £1 coins in 1988/9? I remember using phone cards in 1990 to phone home from university, and them being a bit of a novelty, but I can't remember the largest denomination of coins that coin phones took. I also have a vague idea that pay phones only took four coins at any one time -- am I right about that?
2) About how much did it cost to call the US from the UK off-peak from a phone box? I've got my hero feeding the phone every time there's a lull in conversation, but it'd be nice to know how many coins he needs to start off with. And how many odd looks would he get trying to change a twenty for coins in the corner shop? It suddenly dawned on me that buying a packet of fags with a twenty rather than a tenner might be slightly anachronistic, rather like doing the same with a fifty now.