Jeremy Corbyn speaks at 70th anniversary of Hiroshima ceremony. Peter Marshall/Demotix. All rights reserved.In their opera Iolanthe, English playwrights Gilbert and Sullivan provided a tongue-in-cheek explanation of how British party politics work:

“When in that House MPs divide,

If they’ve got a brain and cerebellum too,

They’ve got to leave that brain outside,

And vote just as their leaders tell 'em to”

Those lines may be more than 130 years old but they ring truer than ever. For British politics, just like all other politics, is made by the party leaders and their whips. In the Houses of Parliament, defiance is not a virtue but usually the quickest way to the backbenches.

Jeremy Corbyn spent many years among Labour’s “rank and file”; now he leads the party. How could Labour’s most notorious rebel become the party’s weapon of choice against David Cameron? How did he gather almost 60% of the votes, dwarfing even the mandate for Tony Blair in 1994, despite defying his party’s line on roughly 25% of all votes over the last 10 years?

The answer is simple: he is Labour’s last resort. If the general election proved anything, it is that even an unpopular Conservative Party, led by a highly disputed Prime Minister, can rack up a landslide victory against a Socialist Party that has long forgotten what its core values and priorities ought to be.

Margaret Thatcher famously called Tony Blair and New Labour her greatest achievement, implying that the party was emulating the Tories and neglecting its principal electorate: working-class Britain. The policies of the Blair governments were no break from Thatcher and Major but a mere extension of their policies by other means.

Corbyn doesn’t plan on rectifying this with some fine-tuning, he will rectify it with the sledgehammer: renationalising the national railways and energy sector, abolishing tuition fees that have skyrocketed over the years and fighting tax evasion at home and abroad are only a few of the actions that Labour’s new leader has proposed.

Although these measures are a very long way from implementation (if they ever will be), they are already symbolic of a far greater project Corbyn envisages: the return of class politics.

Corbyn is the anti-politician. He is neither slick, nor charismatic. He is authentic. All that makes him the complete opposite of David Cameron and that could be his greatest asset. By putting together a Shadow Cabinet that – for the first time in history! – includes more women than men, Corbyn is likely to do well with the female electorate (not exactly Cameron’s strong point) and to prove that his promises of equality are more than just lip service.

The real touchstone of his leadership, however, will not be a domestic issue but the future of UK-EU relations. With the referendum approaching, Corbyn will find himself in a difficult position and will have to prove Britain that he is fit to lead.

The relationship between the UK and Europe is a messy one; it always has been. No party leader has yet found a way to successfully mediate between a largely eurosceptical British electorate and a European Union that grows increasingly disenchanted with the United Kingdom.

While the Labour party, especially under Blair, Brown and Miliband, has traditionally championed the European cause, Corbyn could go down a different path. And while he has vowed to oppose a Brexit, his victory has in fact made it more likely than ever.

Unlike his predecessors, Corbyn is not a Europhile. He voted against continued EEC membership in the first referendum in 1975 and against the ratification of the Lisbon treaty in 2009. Unlike many of his predecessors, Corbyn will not defend Europe at any price, which means that the EU has lost Labour as its most vital and reliable partner in the UK.

Politicians in Brussels believed that in a referendum, they could count on the support of the Labour electorate, but under Corbyn that is no longer guaranteed. The party is likely to keep pro-European talk at a bare minimum and to re-approximate itself to the unions, many of which don’t support the free-market politics of the EU.

Corbyn’s stance on Europe is both similar and diametrically opposed to David Cameron’s: both want the UK to stay in a reformed EU but they fundamentally disagree about the reforms that need to be undertaken.

The PM is pressing for economic growth through more privatisation, free-trade and evidently through less state-regulation. Corbyn was elected on a strong anti-austerity platform, he wants the state to have more power in economic and financial issues and strictly opposes unregulated free-trade.

As the Financial Times argued last week, Corbyn sees membership in the EU as a means of imposing tougher regulations and a new tax on the City of London. His opposition to austerity and free-trade could, however, isolate the UK from two of its most vital allies: Germany and the US.

When bailout negotiations between Greece and the EU reached their latest climax in July, Corbyn helped organise a rally in London to support the cause of the Tsipras-government, calling the negotiations “economic colonialisation”.It is hard to imagine Ed Miliband or any other Labour leader voicing such harsh criticism and it is even harder to imagine Angela Merkel not taking heed of this.

As leader of the opposition, Corbyn’s direct impact on European affairs is, of course, limited. It is without doubt, however, that his position will influence the PM’s stance. Germany needs a strong, conservative, neo-liberal partner in the EU that will support it in fending off stricter regulations and demands from Brussels. The UK under David Cameron does just that. New Labour under Blair and Brown did the same. The prospect of losing this partner and facing a strong opponent of austerity and free-trade is Angela Merkel’s absolute nightmare.

David Cameron’s bluff that the UK can afford to break free from the EU if the latter is unwilling to reform takes its whole legitimacy and credibility (if you think there is any) from the fact that the UK could forge a closer alliance with the US in the realms of trade and defense.

Under Corbyn, the UK would have to give up that trump card. His strict opposition to TTIP paired with his calls to limit the role of NATO and to end Trident are an unstable basis for a stronger partnership with the US. Corbyn’s greatest challenge, therefore, will be to develop his own Third Way: one that adheres to his principles whilst avoiding pushing the UK into splendid isolation from its most vital partners.

When Corbyn was elected, pundits on both sides of the English Channel were quick to joke that this was Labour’s way of refusing to lead in the next years or decades. A certain professional penchant for sarcasm and cynicism aside, there might be a kernel of truth in that statement. Corbyn is no consensus candidate and with an electorate still clustered around a strong centre, politicians from the fringes of the political spectrum are hardly a safe bet. With the next election still years ahead, however, it is far too early for that kind of reasoning anyway.

What is clear is that Corbyn is a rebel in the best possible way. A rebel who will shake things up in the years to come – years that will be crucial to the future of politics in Britain.

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