Originally Posted by SeaBookGuy
I had though "five thirty five" would seem less formal.
In the States, I have heard "quarter of six" but it's rare and pretty much archaic now vs. five-forty-five.
Another one that's U. K. specific is "It's gone seven!" (U. S. = "It's after seven!")
If you're scheduling say a dentist apppointment, would you expect the receptionist to say, "On that date I have something open at twenty past six?" Here you'd likely get " ... I can do six twenty"
Same in the UK when you're doing appointments etc except more likely to be "Is six twenty all right/OK?"... twenty past six is conversational...