“We are living in a period where the seemingly impossible is becoming possible.”

Three months ago, Cambridge’s professor of politics David Runciman may well have laughed if he had heard that Jeremy Corbyn would secure the Labour leadership in a landslide. When we spoke the day after the Islington MP’s triumph, it was a reality.

Professor Runciman heads the department of Politics and International Studies, frequently contributes to The Guardian and the London Review of Books, and has been praised as a writer for his “lucid analysis of very big questions”.

“We live in a time where individuals and groups can push more for disruption,” he says, citing Syriza’s stint in power in Greece. But is this amount of political upheaval good for Corbyn’s party?

“Disruption is the last thing Labour needs,” he says. “Divided parties do not win. If they can’t agree amongst themselves, how can they rule?”

Runciman argues that gaining public support is simple: parties need to display competence, but they can’t do that when they’re divided and Corbyn faces the challenge of maintaining unity in a party where he has long held a position on the ideological fringe.

So how does he explain the general election, for which he correctly predicted the result?

“2015 was the victory of a more plausible prime minister over a less plausible prime minister.”

These concerns over unity and competence are behind Runciman’s belief that Corbyn is likely to do serious damage to the Labour “brand”.

Indeed, since we spoke, the Shadow Chancellor has publicly apologised on Question Time for comments about murdering Margaret Thatcher, and Corbyn has become the first Labour leader to score a negative approval rating in his debut poll.

But if there are such strong concerns about him as leader, how does Runciman explain the Corbyn’s triumph in the leadership election?

“It was an old-fashioned organisational coup,” he explains. “People are simply sick of conventional politics. Corbyn articulates a wide range of policies absent from the mainstream”.

However, the professor seems keen to stress that connecting with “frustrated individuals” is not enough to get him into Downing Street, noting that Corbyn “at most” has the support of a quarter of the population. Corbyn needs to offer more to the rest of the electorate, especially the elderly who are more inclined towards the Tories.

“Electability is the key feature of politics,” he tells me, adding that while Corbyn has indeed got a lot of other praiseworthy things going for him – his commitment to his values, his personable nature, his links to the grass roots – to place these on a pedestal and ignore how central elections are to politics is “crazy”.

“It is wrong to think Corbyn will transform rigid institutional politics and it is hard to see how he could be the person to lead Labour.”

When I ask Runciman whether he thinks the Tories have acquired a monopoly on what is politically possible, he is dismissive of such a simplification of public opinion.

“Cameron and Osborne cannot simply colonise the centre-ground and take it over,” he argues, believing that while the Conservatives have been successful in their “clever spinning of the truth” in attributing blame to Labour for the financial crisis, such a narrative is not hegemonic. He reminds me that “plenty of people still blame the banks”.

I ask Runciman about a recent Andrew Marr article proclaiming the death of the British state. Does he endorse such a view?

“I think Corbyn’s election makes it more broken than it was 24 hours ago,” he argues. The Islington MP’s rise to power could be interpreted as “an advert for seizing the opportunity” that may empower Scottish nationalism. It is no coincidence that talk of a second referendum has been floating around lately.

Runciman isn’t convinced that Corbyn could rescue the Union by bringing the Scots back to Labour, describing him as an “incredibly London politician, he is the London politician, without much appeal to Scotland.” What does he mean by this label?
“What I mean is that his policies may only appeal to a few metropolitan areas.” He is unsure of how far north Corbyn’s appeal can stretch.

When it comes to Scotland’s independence, Runciman considers the likelihood of a ‘yes’ vote in a second referendum “unclear” and believes problems of “institutional reality” such as changing currency significantly weaken the SNP’s support.

The greater issue hanging in the air for Runciman is Europe, which he sees as the “key question for British politics”. At this point, his voice grows particularly energetic as he seeks to impress upon me what an enormously “pivotal” moment it will be for the UK.

Furthermore, he argues that Tory confidence after UKIP’s electoral woes is strongly misplaced, with the referendum offering a “huge opportunity” for UKIP to mobilise their forces and perforate Labour’s stronghold of northern England.

Ultimately, however, he doesn’t think we should be pessimistic about the fate of the British state. Runciman thinks that “the break-up of the union isn’t the end of the world,” and that while the Tories could “easily last 15 years” in power, it is equally true that people soon become sick of those in power.

Runciman calls Corbyn a “megaphone politician”, and is highly sceptical as to what impact he can realistically have.

He even mentions that some are calling for Corbyn to announce a second leadership election for 2018. “He can democratise the party, try and change PMQs, bring new ideas in, but also signal long-term stability.”

Though he accepts that he would “need to be a hard-nosed politician to do this” he emphasises that Corbyn’s ascent to the Labour leadership is proof that “anything’s possible”.

@jackhimself