As Jo Swinson says, tactical voting is the way we can fight back against an unfair electoral system

All that is needed to force Boris Johnson out of No 10 is for the Conservatives and Democratic Unionist Party to lose seven seats between them compared with the 2017 result. And the Lib Dems are currently best placed to win most of those seven

Jo Swinson has scaled back her ambition. She says in her interview with The Independent today that voting for her is the best way to stop a Tory government gaining a majority – rather than proclaiming she could be the next prime minister.

In which case, instead of being accused of arrogance, she should be accused of being rather slow to adjust to shifting public opinion. It was in July that Labour, the Conservatives, the Brexit Party and the Liberal Democrats were each on about 20 per cent in the opinion polls.

Since then there has been a gradual return to a more familiar political pattern, ending in the dramatic collapse of Brexit Party support since 11 November, when Nigel Farage announced his candidates were standing down in half of the seats in Great Britain.