Could his mighty Islington fortress be built a little bit on sand?

We’ve heard a lot about how Boris Johnson is at risk of losing his Westminster seat come the next election. His 5,034 majority over Labour in Uxbridge & South Ruislip is not at all commanding – Labour need just a 5.4% swing to take the seat – and what with Johnson leading the charge towards a No Deal Brexit, with the economic and other disruption that would cause, on top of local issues like Heathrow, the prospect isn’t one to be ignored lightly.

Some commentators have made similar observations about Jo Swinson, who holds a very similar majority to Boris in East Dunbartonshire (although over the SNP rather than Labour). They do so with less justification. There’s no particular reason why, having lost a seat they’d previously gained from virtually nowhere, the SNP would surge back to retake it in the face of a Lib Dem national revival. It’s true that that revival is less marked in Scotland than England or Wales but it’s there all-the-same, and inasfar as Brexit’s concerned the Lib Dems have least to fear of the GB-wide parties from the SNP.

However, there’s one other party leader whose name hasn’t been mentioned as being potentially at risk: Jeremy Corbyn.

“Hang on a minute”, you might well say. “Doesn’t Corbyn have a 33,215 majority, with more than a 60% lead over the Tories? How on earth might he possibly lose that?” Yes, indeed he does. And he very probably won’t lose it. But here’s how he might.

Safe seats can be measured in three dimensions, which for convenience we can call depth, length and breadth. ‘Depth’ is the size of the majority. On this score – the most traditional one – Islington North is one of the safest in the country.

But a more generic description of a safe seat might be ‘one which continually returns candidates from the same party, without significant challenge’. In other words, it’s not just the current majority but the ability to repeat it time after time that matters – i.e. length. On that level, the seat isn’t quite as safe as current numbers would have it. Corbyn’s majority in 2010 was around 12,400 and the election before it was just 6,716 – both times over the Lib Dems. While no-one other than Labour has won it since 1935, the votes haven’t always been weighed in, even relatively recently.

The other dimension is breadth: does the electorate return candidates from the same party across all forms of election? It was this point that should have flagged up before 2015 how vulnerable so many Scottish Labour seats were. Yes, they had big majorities from the 2010 Westminster election, repeating a pattern going back decades, but in council, Holyrood and European elections, their party’s hegemony had already been broken.

And on this point too, Islington North isn’t quite what it first appears. At the Council level, Labour is utterly dominant, holding 47 of the 48 seats (the other being a Green) but like the Westminster elections, this is a recent phenomenon: Labour didn’t control the council between 1998-2010, while for seven of those years, the Lib Dems did. This is not dyed-in-the-wool cultural ‘my-father-and-his-father’-style Labour country. That point was re-emphasised in the recent Euro-elections. Not only did the Lib Dems win across London as a whole then, they also finished first in Islington borough; Labour secured only 28.5% (and the Greens, 19.6%). We should note that Islington covers two seats and they’re not identical but both do have histories of substantial non-Labour votes.

“So what?”, you say. Even if there’s this pre-coalition history and a show of weakness in what’s always been a low-turnout protest election, surely things will return to normal for Labour in a general election, especially for their leader? The coalition legacy doesn’t disappear that quickly? Well, probably. But …

London is a Remainy city and Islington is a very Remainy borough, voting as it did by more than 3:1 to stay in the EU. Therein lies the slim chance for something truly spectacular, because Corbyn is notably not very Remainy, despite his party and despite his constituency. In fact, he wants to leave and demanded the invocation of Article 50 the day after the referendum: points his election opponents will no doubt raise.

If the next election is held this autumn and is dominated by Brexit, as is entirely possible, the Lib Dems are well placed to make very heavy inroads into the Remain vote – especially where they already have an established presence, and all the more so if Labour has a bad conference which concludes with more division and fudge.

Do I expect Corbyn to lose his seat in an autumn election? No. Is it possible if the stars align? Maybe, just. But while Islington North might be a step too far, not least because of the high-profile candidate and the Greens’ presence there, similar factors could well be at play in other constituencies with apparently daunting majorities. These may well offer very good value once odds start being offered on individual seats.

David Herdson