Christian Wakeford became the first Tory MP for 15 years to defect to Labour.
Other Conservatives had quit the party and “crossed the floor” to UKIP, the Lib Dems and Change UK, but not since June 2007 had one joined Labour.
The 37-year-old was elected MP for Bury South in December 2019 as Boris Johnson led his party to a landslide.
But he had a tiny 402 majority in the Greater Manchester constituency after seizing the seat from Labour’s Ivan Lewis, who was elected in the 1997 triumph which propelled Tony Blair to No10.
Before that, the Conservatives had held the Bury South at every election since its creation in 1983.
Mr Wakeford worked his way politics to gain the nomination.
He studied Politics at Lancaster University before working at a telecoms company for four years.
The one-time insurance broker was also a school governor and councillor on Lancashire County Council.
He spent a year working for a Tory MP between 2015 and 2016.
After arriving in Parliament, he made more headlines than many of his fellow 2019-intake colleagues.
Last autumn, he admitted to calling rule-breaking Tory MP Owen Paterson a “c***” to his face after the former minister plunged the Conservatives into a sleaze row over his second job, which led to his resignation from the Commons.
Mr Wakeford told Times Radio: “It's been a mixture of quite a lot of anger and codeine.
“I clearly have a broken ankle at the moment. It's not the best mix.
“But I do think it's fair to show the quantum of anger in the party and that's still happening now."
He also became embroiled in a row in November over a parliamentary trip to Gibraltar when several MPs were accused of getting drunk.
A source alleged Mr Wakeford turned up “hungover” to an event - a claim later denied by a Tory source.
Mr Wakeford did not respond to requests for comment.
On Wednesday night, his profile on Bury Conservatives website was yet to be removed - a poignant reminder of his former allegiance.
“Bury South has been let down by Labour,” he was quoted as saying on August 1, 2019.
“It’s now time for a change and I believe I am the right person to represent the constituency as the Conservative MP, standing up and fighting for residents in the heart of Westminster.”