Most people in Scotland will not have seen an armed police officer, except perhaps in an airport, so there was naturally public disquiet when it emerged recently that it is regular practice for members of armed response units to carry their guns while out on normal duties.

The number of officers involved is small, but the policy, applied by Police Scotland across the country, means it is more likely that, whether in the centre of Glasgow or in a quiet community in the Highlands, officers will be seen carrying guns.

Those with concerns about armed officers on routine patrol had been hoping Justice Secretary Kenny MacAskill might intervene but they were disappointed yesterday when, in a statement at Holyrood, he defended Police Scotland's policy and made it clear he would not interfere in what he sees as an operational matter. "It is essential," he said, "that the chief constable has the operational flexibility he needs to properly protect the public and the safety of his officers."

However, Mr MacAskill was also keen to put the number of armed officers into context. The numbers who are authorised to carry firearms, he said, are low, and represent 1.6 per cent of the total police force. He also said that, because not all of those officers will be on duty at the same time, only a fraction of an already low number are ever out on the streets.

The percentage of Scottish officers authorised to carry arms is also lower than it is in England, where the average is 4.6 per cent and even higher in cities such as London and Manchester, although the policy on armed officers carrying their guns on normal duties is the same on both sides of the Border.

In his statement, Mr MacAskill did move some way to reassure his critics by promising that, if the number of officers deployed on firearms duties routinely exceeds two per cent, the chief constable Sir Stephen House would notify him and the Scottish Police Authority. In effect, this amounts to a promise by Mr MacAskill the numbers of armed officers will not creep up much further, or at least more than 0.4 per cent, and to that extent it is welcome. But what difference does 0.4 per cent make when the problem with armed officers is perception? If Scots see armed officers attending a disturbance at a fast-food outlet in Inverness, it looks like more officers are armed more often, and no procedural promise of a cap of two per cent will change that.

There are other questions to answer, most importantly to what extent Police Scotland is willing to acknowledge that policing should not necessarily be applied in the same way across the whole country, which is what is happening with armed officers.

Also, when a policy as important as where and when armed officers are deployed is changed, it inevitably raises questions about accountability and oversight of the police. Mr MacAskill says the deployment of armed officers is an operational matter, but should it be? And where does operational independence begin and end? These are questions for the police sub-committee at Holyrood to look at as a matter of urgency.