The Bartimaeus series features an alternate London run by magicians who summon demons to do their bidding. As such, it's not quite the real world. However, although there's a reference to American colonies, there's obviously a bit of alternate history going on, since the technology is definitely past the 1700s. That said, it's not really clear how advanced the technology is supposed to be, if it's consistent at all. There are definitely cars, and possibly planes, but they seem to use imps instead of CCTV cameras. Consumer electronics seem to be missing or uncommon, but then, commoners seem to be intentionally excluded from the majority of luxuries.
So what's the general technology level, if any? 1980s Britain, 1960s, earlier? Or even later?