Since then, the EU has doubled its membership. But Lord Owen points to a more recent example: Ukraine. In a lecture last autumn, he noted how the EU blundered its way into a confrontation with Putin by pledging “military-technological cooperation” with Ukraine – suggesting that (as Moscow feared) the EU wanted to become the new Nato. Yet no one in the EU seems to have realised how sensitive the Kremlin was to all this, and how ready it was to act. Ukraine, like Bosnia, was intended to demonstrate the “hour of Europe”. Like Bosnia, it only served to demonstrate that the EU cannot be trusted with security.

All of this is, for Mr Cameron, a tough argument: that far from making us safer, the EU has become a source of instability because it keeps opting for tasks that its threadbare militaries and hopeless diplomats are unable to undertake. A reminder of EU hopelessness came in the Libyan campaign, where member states who were involved in the bombing started to run out of munitions just 11 weeks into the mission. So leaving the EU in charge of security is like asking a choirboy to act as a bouncer in a Swansea nightclub.