Heidi Allen quit the Conservative Party earlier this year, before briefly becoming the leader of the new Change UK Party.
ADVERTISEMENTAnother MP who quit the UK's Conservative Party has announced her decision to join the Liberal Democrats.
Heidi Allen left the Conservatives earlier this year citing concerns over Brexit policies, and went on to briefly become the interim leader of Change UK.
She left after the new party's poor result in the European elections in May.
Allen is now the seventh MP to join the Liberal Democrats since the start of the year, and the fourth former Conservative MP to do so in the last couple of months.
Again citing reasons for Brexit, Allen said in a statement on Monday that she believed the Conservative Party and opposition Labour Party had both "turned their backs on the liberal, progressive centre ground our country is crying out for."
She added: "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."
"My constituents know we are stronger in Europe and they demand better for their country.
"They know that although there is a terrifying amount of work ahead of us, together, we can build a fairer future and more compassionate future for everyone."
In response, Liberal Democrats leader Jo Swinson said she was "delighted" to welcome Allen to the party.
She said: "[Allen] 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."