As an aside we used large ledger type books as diaries and log books at the CRCs. Impossible to destroy locally so we shipped them off regularly to the RN at Faslane who apparently had an industrial scale shredder.
When it came to be replaced after many years and was removed it was found to have broken somewhere inside allowing some items inserted to fall through; and in the foundations beneath were found a very large quantity of intact diaries and log books dating about 10 years....