The Liberal Democrats claim to have a unique selling point in the electoral market. They proudly trumpet their pledge to “revoke Article 50” if they win next month’s election.

It’s easy to make promises you won’t be in a position to keep. There’s no chance of the Lib Dems winning a majority or becoming the largest party at Westminster. They’ll be lucky to win more seats than the Scottish National Party, never mind Labour or the Conservatives. There hasn’t been a Liberal victory in a British general election since 1910, and this vote will be no exception.

But even if Jo Swinson’s party did live up to its own hype, its “Revoke” policy would be a disaster, guaranteeing that the Brexit crisis will drag on for many years to come. Like Boris Johnson and the Tories, the Lib Dems are cynically promising to “Get Brexit Done” (or done away with), while doing their very best to ensure it remains the central issue in British politics.