Insightful reaction by the Economist:

Five years ago, under David Cameron, the Conservative Party was a broadly liberal outfit, preaching free markets as it embraced gay marriage and environmentalism. Mr Johnson has yanked it to the left on economics, promising public spending and state aid for struggling industries, and to the right on culture, calling for longer prison sentences and complaining that European migrants “treat the UK as though it’s basically part of their own country.” Some liberal Tories hate the Trumpification of their party (the Conservative vote went down in some wealthy southern seats). But the election showed that they were far outnumbered by blue-collar defections from Labour farther north.

This realignment may well last. The Tories’ new prospectus is calculated to take advantage of a long-term shift in voters’ behaviour which predates the Brexit referendum. Over several decades, economic attitudes have been replaced by cultural ones as the main predictor of party affiliation. Even at the last election, in 2017, working-class voters were almost as likely as professional ones to back the Tories. Mr Johnson rode a wave that was already washing over Britain. Donald Trump has shown how conservative positions on cultural matters can hold together a coalition of rich and poor voters. And Mr Johnson has an extra advantage in that his is unlikely to face strong opposition soon. Labour looks certain to be in the doldrums for a long time (see Bagehot). The Liberal Democrats had a dreadful night in which their leader, Jo Swinson, lost her seat.

What’s happened to Labour, in other words, looks awfully like what happened to the Democrats in the US in the 1970s and 1980s.