Found it just above the rear subframe - the bracket on the exhaust had completely rusted through but - apart from the back box - the exhaust seems to be the original factory item so 8 years isn't bad! I've botched it with a big jubilee clip for now, but the front hangers look to have stretched by carrying more of the weight. Will get it booked in for a replacement exhaust.

Also reattached the heat shield above where two of the mountings had worn away letting it flap around and rattle. Gotta LOVE big washers!