The answer to any Police or other unwanted activity relating to your or anyones deactivated collection of deactivated 'things' (Never NEVER refer to them as firearms, they're NOT) is in your capable hands Flying 10. Just don't discuss it/them with you mates or others, even out of interest. Keep schtum. The cops can't inspect them unless....... Anyway, they ain't 'weapons.

The actual certificate is merely a duplication or paper confirmation of the mark on the item. If you haven't got one then it is of no consequence at all.