It was revealed earlier this month that up to 1,000 police officers were being trained for possible redeployment in anticipation of potential unrest about border arrangements that could be put in place if the UK leaves the EU without a deal.

However, assistant chief constable Mark Hamilton has said he does not expect the deployment to be necessary.

Police services in the UK can provide policing assistance to each other under a formal “mutual aid” arrangement.

ACC Hamilton told The Detail: “At the present time, we do not have any reason to believe we will need to request mutual aid during 2019, but putting precautionary procedures in place for it is part of a sensible planning process.”

Guidance circulated by the National Police Chiefs’ Council (NPCC) in 2016 states that mutual aid “is usually provided in response to or in anticipation of a major incident or event” and is “likely to be extraordinary to the normal policing arrangements in an area”.

Police officers were deployed to other services on a large-scale and long-term basis in response to public order demands for the first time during the miners’ strike in the early 1980s.