Boris Johnson’s sister Rachel has joined the Liberal Democrats to fight against a “hard Brexit”, according to Channel 4 News.

Ms Johnson reportedly had talks with the party about standing at the general election for them in a target seat.

But she was unable to do so because of a rule requiring candidates to have been members for at least a year.

Her brother, the foreign secretary, played a leading role in the campaign to get the UK to leave the EU.

But their father, Stanley, a former MEP, and Tory MP brother Jo all backed Remain.

Writing in her column in the Mail on Sunday last June, Ms Johnson said the EU referendum result made her daughter cry, while her son’s friends were blaming Boris for “stealing our futures”. Brexit “feels wrong to my stomach”, she wrote.

She has previously revealed that she joined the Conservatives in 2008, inspired by a dinner party discussion with David Cameron in Notting Hill, but left in 2011 complaining she was treated “like the brainwashed member of a cult”.

The Lib Dems are campaigning against a “hard Brexit” that would take the UK out of the single market and end free movement of people – and for a second referendum on the terms of any Brexit deal reached with the EU.