Analysis: 'Show of weapons offers a deterrent effect'

Even if they don't need to carry arms all the time, they should be available for officers in the event of emergencies at train stations and airports.

Scotland should not be regarded as being free of a terror threat and the attack on Glasgow Airport four years ago showed this very clearly.

There could be occasions where the security services have become aware of a target in Scotland at a train station or an airport and the transport police need to respond to this. Some police officers from Scotland's forces are able to carry arms and I don't see why any reason why the transport police should not be able to as well.

If transport police officers in London are able to carry arms, then it makes sense to allow this in other parts of the country, including Scotland. It's something that ought to apply equally.

There are other situations where armed transport police officers may need to be armed.

The issue of dealing with the terror threat is one of the main considerations, but there's also that of dealing with protests that can disrupt airports and train stations.

There was a climate protest at Aberdeen airport in 2009, when the protesters took over a section of the airport and delayed an aircraft that was taking people to hospital, as well as causing problems for a helicopter that was going out to the North Sea.

It took the police a long time to deal with this, but if there had been an armed presence it would have been sorted out a lot faster and the whole airport would have had a lot less disruption caused to it.

It's a not a question of British Transport Police officers pointing their guns at people during these protests. It's more a deterrent type effect and it could also be used by the British Transport Police during public order incidents. The overall point about all of this, though, has to be that other police officers can carry arms, so why can't the Transport Police?

• David Capitanchik is a defence expert at Robert Gordon University in Aberdeen