I have a theory about how this can be turned into a legally defensible method of carrying out truly random spot-checks. It's to do with constant monitoring of FAC/SGC holders, unaudited local "intelligence" databases full of gossip and innuendo ("can't be too careful with gun owners, you know, especially after Cumbria") and no requirement to state the actual piece of intelligence which led to the visit when on the doorstep.
Put it another way. If this gives the police no extra powers at all, then why bother going to the effort of having FELWG put it through top-level stakeholder consultation and getting the minister to sign it off? Qui bono?
My reading of this is that uniformed coppers could rock up on your doorstep unannounced. To stay within the letter of the guidance Plod just needs to say "We have received intelligence that gives us cause for concern about your suitability to hold an FAC. Please will you allow us in now for a chat," while his mate double-checks his list of lawful powers with which to force entry. You know exactly what will happen if you say no in that scenario. What other choice do you have than to let them in? Having let them in voluntarily, many of your legal safeguards are not engaged as they would be if a statutory power or search warrant was used, meaning the two officers have carte blanche to poke around your home on a fishing expedition.
All Plod needs to say, when he stands up in court later, is that an anonymous caller to the new Crimestoppers hotline said they heard raised voices from your home and saw you stomping around the living room with your shotgun. The police are duty bound to act on intelligence received; to preserve the integrity of Crimestoppers the caller's identity and motive cannot be speculated upon.
If enough adverse rumour, gossip or hearsay could be collected on every FAC/SGC holder in the land, that would give the police defensible grounds to carry out spot checks on all of those unfortunates. Hence the new Crimestoppers number.
I want to think I'm wrong, but the more I see of detailed police procedure in this country the more I'm convinced the worst-case scenario is usually the truth.