Professor Peter Jackson, Chair of Global Security (History), the University of Glasgow

THERESA May’s letter to European Council President Donald Tusk to formally trigger Article 50 attempts to link UK security co-operation with the rest of Europe to its bid for a close trading relationship with the European Union. It warns that “weakening our co-operation for the prosperity and protection of our citizens would be a costly mistake”.

Threatening to withhold security co-operation from those states that stand between the UK and the chief threats to its security might seem a dubious bargaining strategy. But such logic has no place in the sound and fury of Brexit Britain. “Your Money or Your Lives”, the front page of The Sun has warned presumably terrified European negotiators.

Members of Mrs May’s cabinet are trying to row back from this thinly veiled threat to use security as a lever in the negotiations. Yet, amid all of this hue and cry an important point has been missed. The idea that Britain will withdraw its intelligence and security co-operation simply lacks credibility. It is in many ways akin to holding a gun to one’s own head to get one’s way.

There is no doubt that Britain brings much to the European table in security and intelligence terms. The jewel in the UK intelligence crown is its membership in the “Five Eyes” intelligence alliance with Canada, Australia, New Zealand and, most importantly, the United States. This grouping marshals unprecedented and truly global powers of intelligence collection and analysis, particularly in the crucial domains of communications and imagery intelligence.

Another major source of Britain’s “intelligence power” is its well-developed structures for coordination and collaboration in the collection, analysis and dissemination of intelligence “products”. These structures are the most advanced in Europe and underpin the struggle against the threats posed by traditional state actors as well as “asymmetric” threats posed by transnational terror and organised crime.

The crucial point to remember is that even the most reliable intelligence is only as effective as the use to which it is put. It must reach the right people at the right time to enable them to act. This is what makes cooperation with Europeans as important as ever. This holds true from the UK’s role in Nato, the cornerstone of British security for more than half a century, to the fight against networks of violent extremists and criminal gangs. In the case of Nato, the emergence of Vladimir Putin’s Russia as a destabilising force in Eastern Europe, the Baltics and the North Sea poses a security challenge that Britain can only deal with in co-operation with its European allies. This is especially true at a time when question marks have appeared concerning American commitment to the North Atlantic alliance. Withdrawing UK intelligence and security support from Nato would be nothing short of self-harm.

This is just as true in the cases of counter-terrorism and organised crime, both of which pose fundamental challenges to the logic of fixed national borders and “national” intelligence and policing. To meet these threats the UK takes part in vast transnational systems of information pooling and coordinated police action.

Europol has made huge strides under the leadership of former MI5 official Rob Wainwright. The UK is by far the largest intelligence contributor to Europol. But it must also be acknowledged that it benefits when its European partners use this intelligence to act against crime and security threats before they reach British soil. The Schengen Information System, meanwhile, constitutes a crucial source of pooled intelligence that underpins the increasingly effective European Arrest Warrant Scheme. UK police and intelligence agencies have used these tools to arrest and repatriate more than 2,200 criminals to other European states.

These mechanisms of co-operation are just as important to efforts to identify and monitor the activities of radical jihadi networks that operate across and beyond Europe.

These capabilities cannot be put at risk. Their importance to UK security is underlined by the considerable resources devoted to intelligence and security capacity building “upstream” in some newer EU states.

The British Government is adamant in its aim to forge a flourishing trade relationship with the European continent after Brexit. The fact is that the flow of goods and services brings with it opportunities for the movement of criminals and violent extremists. This makes security and intelligence co-operation just as important as ever for all concerned.

If the history of the past century tells us anything, it is that Europe and its constituent members are much more secure when they cooperate closely with one another.

Professor Peter Jackson, Chair of Global Security (History), the University of Glasgow