When we still had one pound notes, I heard that the life of a �1 note was about 9 months. �5 now is probably about the same; presumably �10 and �20 notes last longer.
I worked for NatWest in one of there cash centres. All monies paid in are run through a massive german machine called a "G&D", no one ever know what it stood for. All money that was rejected by this machine, whether it was defaced, ripped, or anything else was return to the Bank of England and destroyed.
i haven't a clue i'm afraid. but in america they do the coolest thing! they shread their old notes into tiny pieces and press them together into a block and then sell them to the public. i have a block of $2000 worth of shreaded money xx
it's true - in Australia we have plastic notes. They are rather brightly coloured too, in pink, blue, orange, yellow and green. The life of them is greatly increased over paper, and it makes counterfeiting them virtually impossible.