I have read this through without any comment up to now.
In the circumstances it is my opinion that the police should not have been allowed in - you could escape unreasonable consequences by stressing no Covid protection. However as many have said the police have no RIGHT of entry except by warrant. Where significant suspicion or reasons exist on their part to make a visit necessary, they should ALWAYS give a valid and reasonable reason to ask to enter your premises/home, and you should check, if the slightest doubt exists as in this case - (no covid protection) by dialling 999, as it is an emergency and could result in the theft of firearms - it will also be logged and you should ask for an incident number. Leave them waiting outside whilst you do this. It is not unreasonable for you to check.
In most cases you would expect at most 2 police officers to turn up and offer a reason. 3 is mob-handed and a deliberate intimidation - they could have brought 6 and left four in the car. In my view you should immediately have been suspicious and asked why they wanted entry - for what specific reason did it necessitate a home visit by three officers - they were no more ballistics specialists than porridge makers - the Police have Armourers and that's it and for their own firearms repair, storage, records of issue and replacement. I am lucky, I have been in a Police armaments facility and met the staff.
I would immediately write to your local Chief Constable and Police and Crime Commissioner setting out the facts, the officers names and ask for an explanation under the Freedom of Information Act and pass this on to your MP and ask for his opinion.
It is only by reasonable challenge where the LAW is being unfairly implemented or ignored, can we re-establish the balance, we are not criminals and must be trewated as innocent until proved guilty. It might be a right or a privilege to own a firearm but to me at least it is clear that incursion by the 'establshment' into the clear space between the law and its implementation is as crude a tool as is possible to justify and undermines the RULE OF LAW.
If I stick to the letter of the law - as I must to be a firearm owner and user, so must the POLICE.
One law for them and one for us is the road to closure of the sport and why we should have supporting orgs literally fighting our corner. If you are a member of one ask what they will do about it.