Former Conservative MP Heidi Allen has joined the Liberal Democrats, the party has said.

The South Cambridgeshire MP, who has been sitting as an independent since quitting the Change UK group in June, takes the Lib Dem tally in the Commons to 19.

Lib Dem leader Jo Swinson hailed the MP’s move as “fantastic” news and said she was “hopeful” that more pro-Europeans from other parties would also defect to her party.

Her move follows the recent arrivals of ex-Tories Sarah Wollaston, Sam Gyimah and Phillip Lee as well as former Labour MPs Chuka Umunna, Angela Smith and Luciana Berger.

Allen said: “Shifting to the extremes, the Conservatives and Labour have turned their backs on the liberal, progressive centre ground our country is crying out for. As we face the monumental task ahead of stopping a damaging Brexit, healing the rifts in society and rebuilding the UK, there is only one party with the honesty, energy and vision to do that – and that is the Liberal Democrats under the leadership of Jo Swinson.”

Swinson said: “I am delighted to welcome Heidi Allen to the Liberal Democrats. She has long been an ally in the fight to stop Brexit, and having worked with her I know the energy and passion she will bring to our party.

“This once again proves that the Liberal Democrats are the strongest party of Remain. The best deal we have is as members of the European Union, and I look forward to working with Heidi in order to stop Brexit.”

Allen originally quit the Tory Party in February, along with Wollaston and Anna Soubry, to join the new Independent Group – later renamed Change UK – formed by ex-Labour MPs.

The following month it was announced that she had been appointed interim leader but she left three months later amid reports of disagreements over strategy.

Her South Cambridgeshire constituency is traditionally a safe Conservative seat which she held with a majority of almost 16,000 at the 2017 general election.