Dr Wollaston — Conservative party MP and former GP — took issue with Vote Leave's claim that leaving the EU would free up US$506 million (£350m) a week for the NHS.
MUST-WATCH: She was voting leave, now she’s voting remain – and here’s why:https://t.co/aW6jHW1M4o— Stronger In (@StrongerIn) June 9, 2016
In an interview with the BBC, she said that the assertion "simply isn't true," and that it had made her uncomfortable being part of the campaign:
"For someone like me who has long campaigned for open and honest data in public life I could not have set foot on a battle bus that has at the heart of its campaign a figure that I know to be untrue… If you're in a position where you can't hand out a Vote Leave leaflet, you can't be campaigning for that organization."
Moreover, Dr Wollaston has said that she believes the NHS would actually be negatively impacted by a Brexit vote, as leaving the EU could bring about what she called "a huge economic shock." She has defended her decision to switch sides, saying that a politician who cannot change her mind would be "far worse."
Sarah Wollaston chairs the Health Select Committee in the UK House of Commons, and has gained a reputation for being independently-minded, having rebelled against her own party's government on a number of key votes.
UK citizens go to the polls on June 23 in a referendum on the country's EU membership.