I usually turn mine off on the cut-off; but didn't in September/October. Low and behold, dead as a dodo.
Jumped it and drove about 40 miles and stopped for fuel; turned the key; barely a click from the starter motor!
RAC diagnosed a dead cell and I'm waiting to go to Halfords for a new one.
A new battery will be nice for peace of mind. If that's all that goes wrong with the car, I'll be happy!