Former Conservative MP Sarah Wollaston has joined the Liberal Democrats, the party has announced.
Dr Wollaston was one of three Tory MPs to quit the party in February and join the Independent Group for Change, which she then left in June.
She said she was delighted to now be joining a party making the case for the UK to “remain at the heart of Europe”.
Lib Dem leader Jo Swinson said Dr Wollaston would bring “real expertise” to the party, which now has 14 MPs.
The pro-Remain MP joins ex-Labour MP Chuka Umunna in becoming the second former member of Independent Group for Change – previously known as Change UK – to join the Lib Dems.
The Totnes MP quit the Conservatives in February over the party’s “disastrous handling of Brexit”.
In a Facebook post, she wrote that “after careful thought”, she had decided she could “best serve the interests” of her constituency by joining the Liberal Democrats.
“The Liberal Democrats, under the new leadership of Jo Swinson, are outward looking and unequivocally committed to remaining at the heart of an evolving Europe,” she said.
“In this new political landscape, I feel this is the best political party from which to stand up for the communities I am privileged to represent.”