As Stephen Bush writes in the New Statesman:

The further anti-immigration turn of Theresa May’s government has fixed the Conservatives’ Ukip problem, but they’ve acquired a Liberal Democrat one. Labour, meanwhile, hasn’t fixed its Ukip problem and now as a Liberal Democrat one to match. Blairites used to worry that Ed Miliband was pursuing a 35 per cent strategy (the Labour vote in 2010 topped up with disgruntled Liberal Democrats). It’s fairly clear that Theresa May has decided to pitch her tent towards the 52 per cent who voted Leave, while Tim Farron is going for the 48 per cent who decided to Remain. What Labour wants is to talk about their plans to fix the British economy and negotiate a better Brexit than the Conservatives can. That has the advantage of not putting further pressure on the splits in the parliamentary Labour party and the divide in the party’s electoral coalition. The real risk, however, is what they’ve ended up with is a zero per cent strategy.

In that point lies a potential nightmare for Labour bigger even than having a massively unpopular party leader who is well behind in the polls.

That nightmare is that politics will polarise between new positions which will leave Labour stranded, decaying and unloved in-between much as happened to the old Liberal Party in the early 20th century. Then it was polarisation between workers and employers; this time it could be between Remainers and Brexiteers.

Such polarisation has often been talked about between those who welcome the freedom to move, the interplay of ideas and cultures from different countries and a world that is changing on the one hand, and those who are nervous about new neighbours, who prefer purity of tradition to mixing and evolution and who look back fondly to the past. Paddy Ashdown has long had a good skit about how politics will polarise between those he calls ‘drawbridge down’ and those who are ‘drawbridge up’ – those who welcome others and those who fear others. It’s part of the reasoning behind the core vote strategy which I often champion.

Such polarisation would come with potent danger for Labour with its mix of drawbridge down middle-class voters and drawbridge up working class voters.

It could rip apart at its heart the coalition which forms the Labour Party.