The year is 2020. The Conservatives are in disarray; divided by referendum rebellions and haemorrhaging votes due to rising inequality, house prices and unemployment. Meanwhile the “New Politics” of a certain bearded outsider have brought millions of non-voters to the polling station, returned Scottish constituencies to their Labour roots and attracted supporters of the floundering Lib-Dems and Greens. As the results of the election – a landslide for Jeremy Corbyn – are broadcast worldwide, Donald Trump switches off the Oval office television in disgust.

This vision may be an unlikely one, but stranger things have happened in politics, and a Labour defeat in 2020 is by no means a certainty. Thus it is worth exploring the implications of Corbyn’s foreign policy – what I would term “World Corbynism” – for the UK, its allies and its enemies.

Two important caveats are needed in any exploration of world Corbynism. The first is that, with the party conference having only just concluded, and several years until the general election, the final form of World Corbynism has yet to solidify, and thus predictions can only be based upon the stated position of Corbyn himself, in addition to that of his foreign secretary, Hilary Benn. The second is that Jeremy Corbyn faces significant opposition within his own party, with Tom Watson (the deputy labour leader) and Benn being particularly high-ranked dissenters. Undoubtedly this will mean that many of Corbyn’s expressed policy positions will have to be toned down or abandoned should he assume office.

This process can already be seen at work in the fate of the two most radical elements of world Corbynism; NATO withdrawal and unilateral disarmament. On the first topic, although Corbyn remains against NATO’s political and geographic expansion, he has retreated from previous calls for the UK to pull out of the organisation. Corbyn also still supports unilateral disarmament and has committed to persuading his colleagues on this; however the recent Labour conference made clear the overwhelming opposition he faces. Not only did the delegates vote against debating non-renewal of trident, they also voted in favour of a continuous at sea deterrent, a policy that necessitates full renewal of all four submarines. In addition there has been outspoken opposition to unilateral disarmament from Hilary Benn, Maria Eagle (shadow secretary of defence), Andy Burnham, Paul Kenny (leader of the GMB union) and other influential labour party figures. The probable renewal of Trident in 2016 will make unilateral disarmament still less attractive, since it will then be an active choice to retire updated weaponry, instead of passive retirement of an obsolescent programme.

Disposing of Trident thus seems unlikely to come to pass, but it could be argued that Corbyn’s stated refusal to ever use the deterrent would amount to unilateral disarmament by other means. But this is to mistake the primary purpose of Trident as a symbol of power, rather than an actual weapon to deploy against our current enemies. We do not exist in a situation at all comparable to the mutually assured destruction of the Cold War, so as significant a gesture as Corbyn’s refusal to use Trident is, it is far less important than the actual removal of the missile system itself.

It is telling that despite the absence of his most radical ideas, World Corbynism would entail a jarring break with the post-1980s consensus, as manifested in three main ways. The first would be the reduction in British military involvement overseas. Although Corbyn’s shadow chancellor Hilary Benn has indicated that “we [the UK] are right to be offering air support to the government of Iraq” in the current fight against ISIS, thus indicating the possible continuation of low-grade international interventions, support for airstrikes on Syria (without UN approval) was defeated in the most recent vote. More significant still is Corbyn’s stated desire to only send troops abroad if UN support could be secured. Given the difficulty of avoiding Russian and Chinese Security Council vetoes, this would make overseas interventions incredibly unlikely. Couple this with Corbyn’s long history of pacifism (including chairing the Stop the War coalition) and his expressed doubts about the affordability of the UK’s “global reach”, it is easy to foresee a freeze or reduction in UK military spending. This reduction might become a necessity if Labour is to genuinely attempt fiscal discipline of the sort John McDonnell set out at the conference.

Although the post-cold war era could enable escape from a large and costly military establishment, Britain may face certain unavoidable commitments, most notably over the Falklands. Hopes for the return of Las Malvinas to Argentina have already been raised by Corbyn’s victory (Kitchener describing it as a “triumph of hope”). These are not assisted by the current mixed messages of the shadow cabinet; with Hilary Benn supporting self determination, whilst Corbyn himself has maintained that the islands are “negotiable” and raised the prospect of a power sharing arrangement with Argentina. Much will depend upon the resolution of this internal dispute, but a reduction in British military capability coupled with reluctance to fully commit to the defence of the islands can only increase the chances of future hostilities. Nevertheless the political situation in Argentina is very different from the 1980s (not least given the fall of the military junta) thus making a diplomatic offensive a more probable response to weakness than a military one.

The withdrawal from military interventionism will exacerbate the second major impact of World Corbynism, namely the alteration of the UK’s relationship with its major allies. The “special relationship” between the UK and US will be placed under significant strain for two reasons. Firstly the next US president (be it Hillary or one of the republican field) is likely to be hawkish on foreign affairs, creating a marked divide between them and the non-interventionist, NATO-sceptic Corbyn, who is far more likely to criticise US policy than support it. Secondly Corbyn’s historic links to Hamas and Hezbollah are anathema to the pro-Israel political lobbies in the US, and may engender personal distaste in a relationship (in)famously tied to close personal friendship between PM and president.

The change in our relationship with the EU, presuming a vote to stay in during the 2016 referendum, would be almost as significant. Currently the conservative government supports the free-trade delivered by the EU, whilst being suspicious of its “social” and regulatory aspects. This is a precise inversion of Corbyn’s sympathies. Corbyn “oppose[s] the current austerity ideology” of the EU as well as measures such as the TTIP which he argued showed the EU pursuing “its central goal of being a place where big business has free reign”. At the same time he is a strong supporter of the legislation for workers rights enshrined within the EU. Currently the UK’s closest allies within the EU are Eastern European nations such as Poland whilst countries like France – protectionist and heavily regulated – are its greatest political opponents at Brussels. A reversal in ideological outlook might well reverse these political affinities.

The main direction of World Corbynism seems thus far to be an inward one, a retreat from the idea of maintaining order or peace through intervention or military might, and a loosening of alliances based on trade or joint defence (or, as perceived by Corbyn et. al., exploitation and militarism). But the prospect of World Corbynism does have a more outward facing aspect. This concerns his policies on refugees, retention of the human rights act and an increased commitment to solving the global environmental crisis. The first of these commitments might well win goodwill abroad (specifically in the EU). However its extent remains highly uncertain; although Corbyn has said that accepting 20,000 over the next five years is “far too low” he has also consistently refused to present his own target.

So what will World Corbynism mean for Britain’s place in the world? It will be a diminished one, in which the UK either relinquishes or refuses to use a significant part of its power. To do so will leave the UK relatively exposed; cooling alliances and reheating old rivalries. In this new climate the question of whether Britain’s global power is desirable, or whether it is useful in countering the modern threats of terrorism and cyber warfare, will become moot. A Corbyn government will represent the ultimate acknowledgement that Britain has lost its empire, but also the discovery of a new, more minor but more manageable, role.