Hi phil,
Buy a spare bag from woodbridge ( about £10?).
when you change the bag, put the clean one on.
Empty the main crap into the bin, turn the bag inside out and blast it with a hose pipe.
Leave it to dry and then shake the last bit of fluff out.
Job done.

Cheers
Chris
ps or you could put it in the washing machine

wife wasnt much for that one though :
