Increasingly, the improbable seems to have become the norm in British politics. An upsurge in Scottish nationalism, unsubdued by the ‘No’ vote in last year’s independence referendum, had already shaken past certainties when, in May, David Cameron’s Conservative Party defied expectations and secured an absolute majority in the House of Commons. The opposition Labour Party lost especially heavily in Scotland, with all but one of their Members of Parliament (MPs) losing their seats to the pro-independence Scottish National Party. The inevitable consequence of all of this upheaval – the resignation of Labour Party leader Ed Miliband – was followed by the utterly unexpected: the election of backbencher Jeremy Corbyn, a stridently left-wing advocate of, amongst other things, unilateral nuclear disarmament. Therefore, as a result of this most unanticipated of victories, the issue of Britain’s nuclear deterrence is, after a long hiatus, once again becoming a headline issue in UK politics.
Britain’s nuclear capability rests on the principle of Continuous At Sea Deterrence (CASD), which operates on the basis that, at any given moment, there is at least one Royal Navy Vanguard-class ballistic missile submarine (SSBN) at sea, bearing up to sixteen Trident D5 ballistic missiles, each armed with multiple nuclear warheads. These missile-bearing submarines allow Her Majesty’s Government to respond almost instantaneously to developing crises. Significant levels of technical cooperation exist between the U.S. and UK on Trident missiles, but the force is “operationally independent,” and the authority for its use rests solely with the Prime Minister. Commissioned in the 1990s, the Vanguard fleet’s intended service life was twenty-five years. Therefore, a decision on its future cannot be postponed any longer: after a handful of delays, a “Main Gate” decision on proceeding with the construction of replacement SSBNs must take place in Parliament early next year.
Under normal circumstances, one might expect that the vote, if not merely a formality, would at the very least constitute a straightforward victory for the Government. In 2007, the Labour Government of the time secured an easy majority of 248 for its vote on the principle of Trident renewal, thanks to Conservative Party support (more than cancelling out the revolt of 95 Labour backbench MPs). The political terrain has, however, changed radically since then. To begin with, the Scottish National Party holds 56 of Scotland’s 59 Westminster seats (as well as a majority in the devolved Scottish Parliament at Holyrood). Their opposition to Trident, which is based out of naval facilities on Scotland’s west coast, has shifted the entire nuclear discourse north of the border: on November 1st, the leader of the Scottish Labour party (incidentally a supporter of Trident) watched helplessly as the Scottish Labour conference voted to adopt a policy of opposition to the replacement of Trident. Two days later, the Scottish Parliament as a whole voted against Trident renewal. The significance of this is almost wholly symbolic. The Scottish government does not actually have devolved powers on defense, and the decision to renew Trident will rest solely with the UK Parliament at Westminster.
Enter Jeremy Corbyn. The new Labour leader at Westminster has built a career in opposition, often defying even his own party. In his thirty-two year parliamentary career, Corbyn has made no secret of his opposition to nuclear weapons, and his election as Labour leader has brought no change; indeed, he has been a member of the Campaign for Nuclear Disarmament (CND) since 1966 and currently serves as its vice president. It is unsurprising, therefore, to see him seek to draw his party towards a unilateralist stance. They have, in fact, held such a stance before: in the 1980s, Labour stood against Margaret Thatcher on a left-wing platform which included unilateral disarmament. Labour lost, heavily: their manifesto was later described by one MP as “the longest suicide note in history”.
However, the unilateralist position is no longer popular within the parliamentary Labour Party. The defeat of a (largely symbolic) early day motion calling for the cancellation of the Trident replacement scheme, sponsored by Corbyn at an early stage in his leadership bid, puts the situation into perspective: only 13 of his 232 fellow Labour MPs supported him. By the same token, at the Labour party conference in September, the new leader was defeated in a motion to debate the party’s Trident policy. A major reason for this defeat was the opposition of Unite, an influential trade union and former supporter of Corbyn’s leadership aspirations, on the grounds of the job losses it would entail.
Thus, the situation in Parliament has become hopelessly paradoxical. UK Labour is still officially pro-Trident, although its leader opposes the very concept of deterrence; Scottish Labour opposes Trident, although its leader is still in favor. This may not matter greatly, as British disarmament can hardly be said to be imminent. The Conservative Party still has an absolute majority in the House of Commons, is confident of support from several of the smaller parties, and can almost certainly count on the votes of a significant number of pro-Trident Labour MPs, despite the recent rise in the expected cost of Trident by approximately 20%. The latter may not even have to defy the party whip, as Corbyn has publicly stated that the Trident main gate vote will be a free vote (in a departure from recent Trident Labour votes).
A Labour whip of a Trident renewal vote would likely lead to a major party rebellion. This, in fact, is the broader problem Corbyn faces: he and his Shadow Chancellor, John McDonnell, disagree with much of the rest of the parliamentary Labour Party, and even with many others in the shadow cabinet, on a range of issues. This may not greatly trouble Corbyn, as his power base lies elsewhere. Key reforms in internal party election rules passed by his predecessor, Ed Milliband, vastly increased the power of rank-and-file party members vis-à-vis MPs. Previous leaders were elected via an electoral college model, weighting the influence of MPs, unions, and party members. However, the abolition of this in favor of a single “one member, one vote” system, as well as a concomitant surge in new members granted Corbyn a powerful mandate from the wider membership of the party.
All of this bodes poorly for the Labour Party’s internal cohesion. Britain’s deterrent rests on the premise that those whom Britain seeks to deter must believe that the Prime Minister would plausibly, in extremis, order the use of nuclear weapons. Corbyn, however, has stated in an interview with the BBC that he would not authorize the use of nuclear weapons if he were Prime Minister. His comments were immediately criticized by his own (now former) Shadow Defence Minister, Maria Eagle, who seems to have lost her job after just four months on the post over her support of Trident renewal. His stance has even been critiqued by the ostensibly impartial Chief of the Defence Staff, General Sir Nicholas Houghton – the latter intervention prompting a degree of constitutional controversy within the UK. Party cohesion was further damaged by the appointment of the anti-Trident former Major of London, Ken Livingstone, to Labour’s defense policy review as co-chair – an act which seemed designed to undermine the existing chair, the aforementioned (pro-Trident) Maria Eagle.
If Jeremy Corbyn were to become Prime Minister, his widely-known stance on nuclear weapons use would immediately undermine the credibility of the United Kingdom’s nuclear deterrent. Any policy decision of a Corbyn Government to cease submarine patrols or dismantle key infrastructure would simply be recognizing a reality that existed from the moment of Corbyn’s general election victory. Consequently, if Jeremy Corbyn leads Labour into the next general election, pro-deterrence Labour candidates will be faced with a situation in which the Labour government they ostensibly seek would lead to the destruction of a capability they believe to be vital to national security.
The future of CASD (and with it, Britain’s role in NATO) is not yet in doubt. Corbyn may not survive as Labour leader long enough to contest the 2020 general election. However, the Labour party may have already moved beyond any position that can be easily reversed by the forced removal of Jeremy Corbyn. The new, increasingly leftist composition of the grass-roots Labour party indicates that Corbyn might realistically hope to survive an attempted coup; if toppled, his elected replacement may espouse broadly the same policies. Regardless, the status of the Trident debate would remain the same. In recent decades, Labour has watched gleefully as the Conservative Party repeatedly tore itself apart over British membership in the European Union. Few would have predicted it six months ago, but the issue of nuclear disarmament may yet do the same to Labour.
 That is, a significant number of MPs voting against party line in a whipped vote in the House of Commons. The seriousness depends on the number of MPs and if they are restricted to the backbenches. The loss of a vote after a rebellion may result in a change of party leader.