In this short piece I analyse the foreign and security policy implications of Brexit for the UK and its current European partners. I start from the assumption that whatever the formal position Britain will continue to have vital interests in the international politics of Europe, both because the actions of the remaining members of the EU will significantly affect the UK, and because there are clear limits to what the UK can achieve on its own in foreign policy. On the other hand it will be far from an easy process for Britain to reinvent its foreign policy, whether in relative isolation or as some kind of close associate of the Common Foreign and Security Policy. There is the distinct possibility that both British and European foreign policies will end up worse off as a result of their divorce.
In foreign policy Britain will not have 'regained sovereignty' because it had never lost it in the first place. The Common Foreign and Security Policy (CFSP) is an intergovernmental process based effectively on opt-ins to Common Positions, and with only trivial elements of majority voting. Moreover the EU's two permanent members of the UN Security Council, Britain and France, have never been bound to follow agreed common lines in New York. After a Brexit, however, London will once again have to conduct 'foreign' relations proper with the Member States of the EU, with all the freedom and constraints thus implied, rather than participating in a systematic process of coordination between partners. Indeed, in some respects Brexit will undoubtedly cause tensions with individual EU states, making diplomacy in Europe a new area of importance.
The other side of this coin is an experience the USA has had for many years: wishing to have a seat at the CFSP table but being excluded by virtue of not being a Member State. The USA has found various ways round this by virtue of its status and ability to create special relationships. Britain will have to try the same tactic, but as a country which has damaged the EU by leaving, and as a mere middle-rank power, it will be more difficult. Indeed, having been part of a de facto leadership group in the CFSP with France and Germany it is already finding itself excluded from the new 'big three' of France, Germany and Italy' - although the weaknesses of that group will also soon become apparent.
It is true that this is a two-way street, in that Britain's withdrawal will undoubtedly hurt the standing and effectivenes of European foreign policy. The UK is one of the few countries to mee the UN target of 0.7% of GDP spent on ODA, it is a nuclear weapon state and it is still willing to project military force beyond its frontiers - as Germany and Italy remain reluctant to do. The CFSP will carry less weight without British diplomacy, with its high technical reputation, at its heart. As a result it is possible, even likely, that the EU will take even more refuge in symbolic rather than substantive foreign policy actions such as a European defence community - which would still rely on NATO for actual defence. Equally, the EU will miss Britain's Department for International Development (DfID) more than vice versa. It is, however, possible that Britain's absence will finally force other key Member States to break cover and to accept significant foreign policy responsibilities - while they will also no longer be able to hide behind London's opposition to majority voting on foreign policy. If they fail to come up to the mark, and European foreign policy fades from view this would weaken Europe in the world, and by extension also British interests.
One undeniable fact which the Brexiteers will have to face is that Britain cannot do without multilateralism in some form. And it will not be short of fora in which to engage, given its memberships of NATO, the Commonwealth, OECD, G8 and the G20, besides the UN system. Thus there will be plenty of scope for ad hoc issue-based coalitions. This will be vital for actions like economic sanctions - Britain can hardly impose them on its own - and for 'milieu' goals such as the management of climate change, where the UK will certainly want to associate with its European ex-partners. Furthermore Britain should still be a likely candidate for the various Quads and Quints which exist as shadowy contact groups, cutting across the formal institutions. The 'Five Eyes' intelligence grouping of the US, UK, Canada, Australia and New Zealand is a particularly important example. Still, none of these groups, formal or informal, are foreign policy-making organisations in the way that the CFSP is. Furthermore British security interests are still primarily regional rather than global, and London knows that only the EU can seriously expect to act as a stabiliser of the European neighbourhood.
Migration and terrorism have shown in recent years that the distinction between internal and external politics is blurred and complex. Thus for Britain no less than for France, Italy or Spain foreign policy and what the EU calls 'freedom, security and justice' issues are inextricably connected. The UK will need cooperation on arrest warrants, airport security and counter-terrorism even without a formal relationship with the EU. What is more if it continues to pursue interventionist policies in the Middle East there will be consequences for the whole region which may well lead to tensions with the EU and its members. It is true, on the other hand, that Britain has already marginalised itself in many respects, through such things as its absence from Schengen and the euro, its opposition to an operational military HQ in the EU, and its unwillingness to even envisage a common migration policy. On Ukraine it was outflanked by French and German diplomacy long before the Brexit vote.
The issue of bilateral relationships is going to be very prominent for the UK over the years ahead. France in particular is a key imponderable. In many ways foreign policy binds London and Paris together, as the only two European nuclear weapon states and permanent members of the UNSC with global security responsibilities - if not capacities. The two states have had a special defence relationship since St. Malo in 1998, reinforced by the Lancaster House treaties in 2010. Equally importantly, both have struggled to cope over the last half century with the end of extensive colonial empires, and with the ties and resentments they engendered. Geography, with the running sore of the Calais migrant camp, the uncertain future of the Treaty of Le Touquet, and the vulnerability of Britain to French nuclear accidents, also still plays an important part.
France is mightily irritated by Brexit, but also alarmed by the likely loss of its foreign policy equivalent. It can now act for the EU in the UNSC without reference to Britain, but is unlikely to benefit much from that. More significant is the fact that it will be more exposed to criticism within the EU as the only nuclear weapon state in a foreign policy system committed to non-proliferation. For its part the UK cannot afford to distance itself from France, both in terms of the latter's influnece over European integration and as the only state with whom it can act as a balanced duopoly - the Balkans in the 1990s, and Libya in 2011 being the cases in point. There will not be much leverage in going cap in hand to Washington for a restoration of the US-UK 'special relationship', and not much domestic support for that either. Britain will also have to court Germany, as the most powerful Member State, able to shape the terms of the eventual Brexit and with the potential to take an ever higher foreign policy profile.
Outside the EU, the UK will have little option but to seek privileged relationships with a wide range of significant states, not least driven by the need for trade agreements. These third parties will thus gain some leverage on foreign policy matters. Given the Commonwealth network India, Australia, New Zealand and Canada will be prominent in this, which will be a poigant reversal of their role as demandeurs when Britain was negotiating to join the EC in 1970. Other key states which UK diplomacy will have to focus on, inherently demonstrating its increased weakness, are Brazil, Japan, South Africa, South Korea and Mexico. but one trope which will do little for Britain in this process is its traditional boast of acting as a 'bridge-builder' between differing regions and groupings. A country which cannot speak for Europe will have no credibility as an indispensable country.
One temptation - indeed necessity - will be to fall back on the UK's famous 'soft power', consisting of the English language, financial services, educational achievements, vibrant arts and sciences and historical fascination. But on most of these indicators Britain's position is slipping, partly through other factors than Brexit, but certainly not made better by its prospect. University courses are now being taught in English across the continent, reducing Britain's comparative advantage. The City of London will probably survive even expulsion from the Single Market, but its banks, personnel and reputation are bound to drain away to a degree given competition from Frankfurt and Paris, just as some high tech firms are already being lured to Berlin. Much depends, of course, on how far the EU itself remains a zone of civility and prosperity - if populism sets in with a vengeance and Britain's version of multiculturalism remains stable, then the UK will appear to many to be the kind of safe refuge from turmoil that it did in parts of the 19th century, the 1930s or the 1970s.
The last area of substantive difficulty facing UK foreign policy as a result of the referendum vote relates to the policy process. As Sir Peter Ricketts, Britain's most experienced diplomat of recent years, has asked: 'with all the effort needed for the multiple sets of negotiations arising from Brexit, will the Government have the bandwidth for an active foreign policy as well?'This is partly a matter of psychologicval and political distraction - the UK is going to be turned inwards on the Brexit project and what will continue to be severe internal divisions for some time to come. But it is also a simple question of insufficient personel. The UK has to find the trade negotiators it has not needed these last four decades. It will be out of the European External Action Service. It will be desperate to use all those in its administration - ie not just the Diplomatic Service - with the ability to engage with foreigners (as other Europeans will increasingly, and sadly, become) to work on the huge complexities of disengagement from the EU, on negotiations with third countries and on damage-limitation world-wide in relation to our reputation. New international initiatives and 'global responsibilities' will be at the bottom of the list of priorities.
In conclusion, Britain will face a theoretical choice, as Richard Whitman has pointed out, between three possible post-Brexit foreign policy roles: integrated player, associate partner and detached observer. But the choice will not be the UK's alone even assuming that the usual pattern of muddling through rather than rational strategy does not prevail. The 27 EU Member States will not make things easy for the UK, even if many of them recognise its value as a foreign policy partner. As Britain cannot have a seat at the policy table, it will have to rely on informal, even secretive, back-channels, as often as not post hoc. Even if it feels it can align itself with a Common Position, it will be chasing the game when it comes to implementation, having no say over the use of the economic and political instruments of EU diplomacy.
Left more to its own devices it is unlikely that the UK will compensate by being able to increase its spending on its own external policy resources, particularly the horribly expensive area of defence. British relative power in the world will decline, robbed of such economies of scale as are currently available to it. Indeed, if the EU does ever succeed in making its own saut qualitatif as a major foreign policy player then Britain will fianlly come face to face with its worst historical nightmare: a united continental power, and one not susceptible to the carrots and sticks of a 'balancer' outre-Manche.
Professor Christopher Hill, University of Cambridge
 Sir Peter Ricketts, 'What will Brexit mean for the UK as a foreign policy power?', ESRC project UK in a Changing Europe, 12 September 2016, http://ukandeu.ac.uk/what-will-brexit-mean-for-the-uk-as-a-foreign-policy-power/ accessed 28 September 2016.
 Discussion paper, private Chatham House meeting.