As the key leave campaigner Boris Johnson said in his biography of Winston Churchill two years ago, the European Union, together with Nato, “has helped to deliver a period of peace and prosperity for its people as long as any since the days of the Antonine emperors”.



While it may have only been 70 years since the end of the second world war, rather than the 200 years that the Pax Romana lasted, the modern EU does provide Britain with unique cooperation and access to intelligence in counter-terrorism, security and home affairs.

Outside the EU, Britain would still have its intelligence relationship with the US and remain part of the Five Eyes – the US, Australia, Canada, New Zealand and the UK – the closest international intelligence-sharing arrangement in the world. No doubt there would also be bilateral data-sharing with individual EU countries about terrorism and crime.

But Brexit would also mean no access to the European arrest warrant, which has seen 5,000 people speedily extradited from Britain to Europe in the past five years and 675 suspects or convicted criminals to Britain to face trial or serve a prison sentence.

Before the arrest warrant existed it took 10 years to extradite Rachid Ramda from Britain to France over his role in the 1995 Paris Métro bombing. In 2005 it took just 56 days to bring the failed 21/7 London tube bomber Hussain Osman back from Italy to London using an arrest warrant.

The home secretary, Theresa May, has said that while Britain will never sign up to a European police force or European public prosecutor, it does participate in a wide range of practical agreements that have “made a positive difference in fighting crime and preventing terrorism”.

They include the European criminal records information system; the financial intelligence units; prisoner transfer deals; Schengen information system 2; joint investigation teams; and the Prüm convention, which allow Britain to turn away more than 3,000 criminals at the border, prevent money laundering, send foreign criminals back home, carry out cross-border investigations and share forensic data such as DNA, fingerprints and, more recently, passenger name records much more quickly.

The idea that Britain inside Europe is less safe because it is not allowed to control its borders is also open to question. Britain is in the EU without being part of the Schengen area – the EU countries without border controls between them – which means checks can be carried out on everyone entering the UK and the entry of terrorists and serious criminals blocked, including those coming from the rest of Europe.