I recently received a P60 form, with the usual reminder to "save it in a safe place". Unfortunately I usually do, then forget where.
With the much reduced costs of modern technology I wonder if it would be better to scan it first, plus somehow tag it as a file, and only then put the original in a safe place.
It should work for most documents for which scanned copies or photocopies are acceptable.
It probably wouldn't work for documents such as CRB paperwork, which causes interesting effects if put through a photocopier.