Reform UK has played a blinder - or perhaps Rishi Sunak has just fumbled the bag. Whichever way you see it, the political landscape has shifted.
Without a general election - or one of the endless by-elections that have been fought in recent weeks - Richard Tice's party has secured its first sitting MP.
Lee Anderson crossed the floor on Tuesday, sitting on the opposition benches next to disruptor-in-chief George Galloway who beat the Tories and Labour to first place in the chaotic Rochdale by-election the month before.
Even when Anderson was a member of the Tory party, and even in his party role as deputy chairman, he still had the ability to be a thorn in the PM's side. But now he's crossed the floor, Rishi Sunak should be prepared for the problem to grow.
Reform UK has played a blinder - or perhaps Rishi Sunak has just fumbled the bag. Whichever way you see it, the political landscape has shifted
PA
Lee Anderson loves to be a contrarian and to push boundaries. But more than that, he puts his personal views above allegiance to party politics. Just look at the career jumps he's taken. First a Labour councillor, then a Tory MP and now he's back on the opposition benches with Reform.
Anderson, who is the only MP of his party, is expecting to get questions every five to six weeks at PMQs. He plans to ask as many as possible, even weighing up asking questions submitted by GB News viewers. There is no doubt that he will use his short pre-election stint on the opposition benches to cause at least a few headaches for the Prime Minister.
But as well as being hard to pin down and good at causing a scene, he also has local appeal.
There's always a concern when an MP defects that the people who voted for him, campaigned for him or donated money would feel betrayed. In theory, he no longer represents the values he was elected to represent.
But perhaps Anderson's personal brand of politics - which is evidently so much more about his individual views than it is about party politics - can shield him from this effect.
GB News reporter Will Hollis went to his Ashfield constituency on Monday, just hours after he announced his decision to defect. And rather than feel betrayed by his decision to cross the floor, many empathised. Many of them firmly said they'll be sticking with Lee.
David Lindley told GB News he backs Anderson because he "gets things done".
While fellow constituent David Wood added: "He's the only MP that speaks his mind. You can't vote for the Conservatives anymore and you can't vote for Labour, so he's done right. He's the best MP that's in the parliament at the moment."
While one person who spoke to GB News on Monday, Matt Wilkinson, said he wouldn't be voting for him, the 23-year-old said it is because he never would have done so before. Crucially, Anderson's defection didn't change his appeal.
But the MP's decision to cross the floor and join Reform UK goes deeper than just his constituency.
The fledgling party has spent months desperately trying to persuade voters that it is a convincing electoral force. A big deterrent for voters considering backing Reform is the idea that it might be a wasted vote. But what better way to persuade voters that they're a serious party, than by doing a show-and-tell with their already sitting MP.
One Conservative insider, who described the situation as "a big problem" for CCHQ, said many people are "more loyal to the MP than they are to the party" - something they said is likely to be repeated across the UK should any others defect.
But a Reform insider played down the prospect of any MPs following Anderson. Asked about it, they said: "Not yet. Not right now."
While there have been rumours of as many as nine other MPs considering a defection, the insider said it will take more boat-rocking from inside the Tory party to create a meaningful swathe of MPs crossing the floor.
But they agreed that the "political landscape" has changed entirely since Anderson's defection.
His decision to join the party is likely to go some way in persuading voters that it can actually return MPs, rather than just being a sideline party that's going to do nothing.
At its most basic level, having someone like Anderson as their first sitting MP is a fantastic marketing tool.
But it also exposes yet more weaknesses in the Tory Party.
It's not hard to poke holes in the CCHQ campaign machine right now. But Anderson's defection has yet again highlighted a gaping one: Sunak's leadership.
Just two months ago, the MP for Ashfield told GB News that Reform UK leader Richard Tice is a "pound shop Nigel Farage". He tore into the party, saying it will be the reason Sir Keir Starmer comes to power.
Fast forward to last week, and Anderson is standing side-by-side with Richard Tice, promising to "get our country back" under the Reform banner.
Yes, perhaps it does speak volumes about Anderson's grip on his own beliefs. But it also shows how far the Tory party has fallen for him to turn his back on them and head towards a party that, at one point, he clearly saw as the dark side.
Perhaps it signals an acceptance that it won't just be Reform's fault if Starmer wins the election. Anderson, like so many voters turning their backs on the Tories, appears to have started to pin the blame at the source.
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His defection came just a week after the Budget, which many saw as a damp squib. Despite the party pinning its hopes on the fiscal event as a tool to claw back some of Labour's lead, it failed to deliver any form of poll bounce for the party. Perhaps that was what sealed the deal for Anderson.
But regardless of what was the final nail in the coffin, Sunak's failure to see it coming is jarring.
It has long been said that Rishi Sunak isn't a great politician. People will rarely deny that he's clever, good at maths, a hard worker - even a kind person. But when it comes to political manoeuvring, persuading people to get on side and making savvy choices to shore up his own position - there are few that will come out to bat for him.
One Tory insider on the right of the party told GB News that Downing Street has "always underestimated the genuine threat of Reform". They claimed they had "personally" warned Sunak that something like this could happen more than a year ago, but said: "He just didn't get it."
Speaking about the PM, the insider added: "You can’t fight an already very tough general election on both flanks. The sad reality is he’s just not very good at politics."
Another party source said the PM was "completely blind" to the threat posed by defections.
Looking at Sunak's decision to cast Anderson out from the party with no recourse to return, it is unsurprising that Tories are frustrated.
Regardless of your view on Anderson's remarks - which saw him say "Islamists have got control of our country" and that London Mayor Sadiq Khan has "given our capital city away to his mates" - it is hard to deny that on a political level, throwing a big hitter like Anderson to the wolves was unwise.
Reform UK has put in decent shifts in recent by-elections. They took 13 per cent of the vote share in Wellingborough and 10 per cent in Kingswood. But as GB News reporter Jack Walters points out in this analysis, so far, they haven't been doing as well as they could be.
But they've played a blinder this week with Anderson - and it may well change the course of their election campaign. At worst, it will leave the Conservatives even more bruised than they were before.