The post-war international order began to take shape aboard two warships anchored in Placentia Bay, Canada, 80 years ago in the summer of 1941. This was the setting for the first of the great Churchill/Roosevelt wartime summits. The result was a shared vision of the future peace, set out in a joint declaration known as the Atlantic Charter. Much of it was drafted by the British diplomat, Alexander Cadogan.

This document served as a blueprint for the great surge of institution-building in the late 1940s. Churchill and Cadogan persuaded Roosevelt to sign up to the concept of a “wider and permanent system of international security,” which paved the way for the United Nations. Principles which became the bedrock of the UN Charter—non-use of force, territorial integrity, self-determination—all came out of the Atlantic Charter, in some cases word for word. Nato was another product of the Anglo-American alliance forged in Placentia Bay. The success of Cadogan’s generation in transplanting British ideas into durable institutions in cooperation with the US has lessons for today’s policymakers.

The framework for international cooperation built in those post-war years is now under unprecedented strain. Every country is recalibrating its foreign policy in response to the changing geometry of global power and the impact of the pandemic. But Britain embarks on its post-Brexit future at a time of particular national weakness, deeply divided internally, alienated from its nearest neighbours, and coping with the largest fall in GDP of any G7 country.

The government’s Integrated Review of defence and security published in March marked a first step in distilling a new national strategy. It set out plenty of ambitious objectives for global Britain. But the effect was spoiled because the government forgot that actions speak louder than words. For example, the Review proudly presented Britain as a soft power superpower and a force for good in the world, standing up for human rights and the rule of law. That is indeed an important part of our national identity. But the abrupt cut in the aid budget and the threats to break a binding international agreement with the EU have undermined confidence abroad that Boris Johnson’s government really is committed to living the values it proclaims.

Britain now faces four crucial choices in its international relations, which will shape our national strategy for decades to come.

First, can we collectively come to terms with the fact that Britain is no longer a great power? The Integrated Review gets part way there. Much of it is written on the basis that Britain is a significant middle-sized country which has to work with allies in order to have influence. But a strain of Rule Britannia exceptionalism keeps breaking through. The lesson of Cadogan’s success is that Britain can again be a creative force in organising new forms of cooperation for the post-pandemic world, provided that we have the ideas and are willing to put in the sustained effort to win the confidence of those with more influence than we have.

Second, are we prepared to accept that the inevitable lot of a middle-sized country is to make awkward compromises with more powerful economies? That will be especially true in negotiating trade deals. For all the claims of taking back control, Britain will also find itself constantly having to accept rules and standards set by others. When the US and the EU differ, for example over food standards or data protection, the UK will have to choose. Without the protective cover of EU membership, Britain will also be more exposed to retaliatory actions when speaking out on human rights abuses in countries like China and Saudi Arabia. Difficult trade-offs will be needed.

Third, can we work out a China policy which suits British interests within the force field of US/China confrontation? On national security issues, London will always line up with Washington. But the UK has more of a need to maintain a working relationship with Beijing across a broader front than the US, not least because the new barriers to trade with the EU make access to the fast-growing Chinese market even more important for British businesses.

Fourth, how long will we take to re-discover that British interests will remain intimately bound up with what happens on the continent? The Integrated Review at least recognised that European security was a precondition for global Britain. But, tellingly, the EU itself barely got a mention. The government envisages working closely with France and Germany on defence and security. But in reality it will be impossible to keep that cooperation insulated from a rancorous economic relationship with the EU. Britain’s defence industrial cooperation with France has already suffered. Our influence in the world will be weakened until the government can bring itself to build a productive new relationship with the EU.

In short, Britain is still a long way from working out a new national strategy to replace the balance between our European and wider-world interests which has served us well for 70 years. Achieving that needs a much wider debate. My new book Hard Choices will, I hope, be a stimulus for that public conversation, which should as a priority involve the younger generation. Their lives will be most affected by the decisions we make collectively in the years ahead. When those now in their 20s and 30s get their hands on the levers of power, I am confident they will find creative new answers to the hard questions about Britain’s place in a fast-changing world.