David Frost
There is no legal deadline, which is rather odd when you think about it.

You couldn’t reasonably expect the police to turn the renewal round in time if you only got your application in the day before!

I recommend you aim to get the paperwork in at least eight weeks before expiry which will give reasonable time for the police to do their side of the business.

If for some reason you can’t make the eight week deadline drop them a line or give them a ring to explain why.

Whatever you do don’t send in the expiring certificate because you may need it for a variety of reasons.

If, after giving eight weeks notice, you don’t get the certificate back on time you should insist on being given a Section 7 temporary permit.

There is no other way in which you can remain in lawful possession of your guns if the certificate is not renewed.

A letter from the Chief Constable saying it’s okay to keep your guns whilst his staff get around to doing the renewal has all the validity of an old catalogue in the privy at the bottom of the garden.