I think when I was on YY64 GWX back when it was being trialed on the X21 it ended up losing a windmirror just after leaving Gateshead Interchange. Other than that I don't think I've ever been on a bus in an accident.
Though I'd probably narrowly avoided being in one yesterday when the driver of the X21 I was on slammed on the brakes at the start of the roadworks on the A1, as everyone was being forced into one lane due to an accident further up.
RE: Bus incidents