Britain's lonely future, outside Europe and stripped of Nato, is a national security threat

The German Chancellor has predicted Britain's future after Brexit quite accurately: a stumbling economy, failing public services and depressed living standards will be joined by a smaller voice in the world

Angela Merkel joins drinkers in a beer tent in Munich on Sunday. The German Chancellor has warned that Europe can no longer rely on the US and UK in the manner it has since 1945 (Getty)

For all the talk about Brexit, Donald Trump and a global populist insurgency, the most successful democratic politician of the West so far in the 21st century is a pragmatic, unshowy figure from the Europhile centre right. Angela Merkel, so far as can be judged, is cruising towards a fourth consecutive term as Chancellor, having made the historic decision to permit one million Syrian refugees to come to Germany. She is a reminder for anyone who cares to look that politics can be mature.

So Ms Merkel carries considerable weight and, when she warns Europe that it will need to look increasingly to its own structures and resources to secure its future prosperity and security, she will be heeded.

Increasingly outspoken, with Germany gradually learning to assert itself, she has spoken almost despairingly of no longer being able to rely on the UK and the US in the manner it has been used to since 1945. She is right, too: President Trump may be less disparaging about Nato than he was on the campaign trail, but he remains equivocal; his relationship with Russia still uncertain. On climate change, the US President seems to take some malicious pleasure in making friends and allies wait for his final verdict, as if he were some judge on a reality television show pausing for dramatic effect before announcing a winner. Overall, Mr Trump is living down to expectations. No wonder the German Chancellor is not prepared to accept his clowning around.

Ms Merkel is also right to point to Britain's growing isolation, if not alienation, from Europe. Whoever wins on 8 June, the UK will be led by a more or less Eurosceptic prime minister, committed to whatever Brexit deal can be rescued from the current wreckage.

If it is Theresa May, as is apparent from her Article 50 letter, she will be prepared to sacrifice UK security interests in the name of Brexit. She is also apparently willing to use the future of EU citizens living and working here as negotiating cards. And she will impose limits on the free movement of goods, services and people as the inevitable result of exiting the single market and the EU customs union.

Events such as the G7 conference bring into sharper focus what a lonely existence the British will soon have: a stumbling economy, failing public services, depressed living standards will be joined by a smaller role and voice in the world.

There is little sign that the global influence we now exert via the collective clout of the EU will be replaced by closer relations with the US, let alone China, Russia or India.

Some obvious vital interests will be more vulnerable, such as the status of Gibraltar and the Falklands. Much more important, if Nato does start a gradual decline in power and relevance under President Trump, and some form of EU defence capability emerges to replace it – long an ambition of European federalists – then the UK will be left to assemble its own defences without the collective security offered by Nato or the EU. With a nuclear deterrent which has proved irrelevant in every conflict since the Second World War, and which is in any case highly dependent on America, Britain has only its much denuded conventional armed forces and intelligence services to see off threats at home and abroad. They are highly professional, brave and among the best in the world, but they are no substitute for the leading role Britain used to play in the EU and Nato.

Angela Merkel is right in her implication that a lonelier future lies ahead for Britain.