One of the cardinal and much-cherised principles of the British democratic system dating back to 1829 has been policing by consent. This is the idea that the police earn the right to exercise their powers by society’s approval, based on transparency, accountability and integrity.

Another valued tradition, which sets us apart from the US and other countries, is that British police are not usually armed. Seeing officers on the street with handguns or automatic weapons tends to makes us feel uncomfortable, rather than secure.

Unfortunately, these principles seem to have been ignored on the Rosneath peninsula, where the UK’s nuclear weapons are housed. As we report today, the Ministry of Defence (MoD) police who guard the Coulport and Faslane nuclear bases are planning to increase their activities across the area.

MoD police are routinely armed, and in the past have focussed on preventing crime and terrorism on nuclear sites. They also regularly apprehend protestors who try and block the nuclear bomb convoys that travel by road the length of the UK.

Now concerns have been raised locally about their expansion plans on the Clyde. MoD police are stepping up spot checks on cars, and increasingly quizzing people who take an interest in nuclear submarines to ascertain, in the words of one MoD officer, “whether you are a friend or foe of Argyll”.

The motives and behaviour of the MoD police may be admirable, but there are real questions to answer about their ambitions. Will they respect civil rights? Do they really understand how to police communities? Are they compensating for cuts in Police Scotland local cover?

It is also odd that Police Scotland hasn’t commented, and that the local SNP MP and defence spokesman, Brendan O’Hara, doesn’t seem that bothered. They should be pressed to say more.

This is not an argument about some little local policing problem. It goes to the heart of the precious tradition of policing by consent, and should be taken seriously by our police and our politicians.