Conservative MP Natalie Elphicke has defected to the Labour Party, saying the Tories “have become a byword for incompetence and division”.

In a statement released just as PMQs was starting, the MP for Dover said the key factors for her decision were housing and border security.

She accused Rishi Sunak of “broken promises” and abandoning key pledges.

It is the second defection to Labour for Rishi Sunak in less than two weeks, after Dan Poulter also quit the Tories.

Labour will retain their existing candidate in Dover and Deal at the next general election and Ms Elphicke will stand down, the BBC understands.

The constituency replaces Dover, where Mrs Elphicke had a majority of 12,278 at the last election, following boundary changes.

In dramatic scenes, Prime Minister’s Questions began in the Commons with Mrs Elphicke crossing the floor to sit behind Labour leader Sir Keir Starmer.

There was bemusement and confusion from many on the Conservative benches.

The news has only been announced at midday and plenty of Tory MPs had not realised that their former colleague was now sitting opposite them – directly behind Sir Keir and so in the camera shot when he is talking – rather than on their side.

Sir Keir welcomed her to the party, asking Mr Sunak “what is the point of this failed government staggering on” when “the Tory MP for Dover on the front line of small boats crisis says the prime minister cannot be trusted with our borders and joins Labour”.

Dover is the arrival point for many people who cross the Channel in small boats.

In her statement, Mrs Elphicke said Mr Sunak’s government “is failing to keep our borders safe and secure”, with lives being lost in the Channel and small boat arrivals “at record levels”.

A Conservative Party spokesman said: “The people of Dover and Deal will be disappointed having felt the impact of illegal immigration.

“They did have an MP who sat with the party fighting to tackle this issue head on, now they have an MP in a party that has worked to block our plans to tackle illegal immigration 139 times.”

Last April Mrs Elphicke wrote in an article for the Express that Labour had “no plan of their own to tackle illegal immigration” and described the government’s Rwanda plan as “world-leading”.

However, more recently she said she feared legislation aimed at reviving the plan would not stop small boat crossings, and suggested a returns agreement with France would be more effective.

Labour has pledged to scrap the scheme, which would see some asylum seekers sent to the east African country, if it wins power.

Asked whether she had changed her mind on Labour’s immigration policies, Mrs Elphicke said Mr Sunak had not stopped small boat crossings and Labour would tackle this issue.

The MP said she had not been offered a peerage to defect but had been asked to contribute in the area of housing.

Sir Keir said Mrs Elphicke had a “strong track record on issues such as housing” and was “on the front line when it comes to the crisis of small boats”.

Transport Minister Huw Merriman said he was “absolutely staggered” by the defection and accused Mrs Elphicke of being “opportunistic”.

“Just recently she’d written an article… saying don’t trust Labour on immigration, they really want open borders, and now she’s sitting with them,” he told the BBC.

“Absolutely bizarre.”

Former Labour leader Lord Kinnock told BBC Radio 4’s Westminster Hour: “I think we have got to be choosy to a degree about who we allow to join our party because it’s a very broad church but churches have walls and there are limits.”

He added: “Mrs Elphicke has got to decide whether she is committed to the programme and principles of the Labour Party, broadly defined, generously defined with great liberal intentions, but we are a political party and not a debating club.”

Mrs Elphicke, who supported Liz Truss in the 2022 Tory leadership contest, was on the right of the Conservative Party and a member of the Brexit-backing European Research Group.

Sir Keir’s decision to welcome her to Labour has come in for criticism from some on the left of his party, particularly as Diane Abbott and Jeremy Corbyn remain suspended from the Parliamentary Labour Party.

Left-wing campaign group Momentum said: “This hard-right Tory should have no place in a Labour Party worthy of the name.

“It speaks volumes about Keir Starmer that he is welcoming her with open arms, while leaving Diane Abbott out in the cold.”

On housing, Mrs Elphicke said the government was “failing to build the homes we need” and had “betrayed” renters and leaseholders by not delivering on promises to end no fault evictions and abolish ground rents.

“When I was elected in 2019, the Conservative Party occupied the centre ground of British politics,” she said.

“Since then, many things have changed. The elected prime minister [Boris Johnson] was ousted in a coup led by the unelected Rishi Sunak.

“Under Rishi Sunak, the Conservatives have become a byword for incompetence and division. The centre ground has been abandoned and key pledges of the 2019 manifesto have been ditched.”

By contrast she said Labour had “changed out of all recognition” since 2019 and now “occupies the centre ground of British politics”.

She added that the party had a “plan to build the homes we need” and its economic and defences policies “are responsible and can be trusted”.

Mrs Elphicke was elected in 2019, taking over the Dover seat which had been held by her disgraced then-husband Charlie Elphicke.

He was jailed for two years in September 2020 for sexually assaulting two women.

It comes after former minister Mr Poulter also defected to Labour, over the Conservative’s record on the NHS.

This is the fourth Conservative defection since 2019.

Lee Anderson, who sat briefly as an independent, joined Reform earlier this year, while Christian Wakeford left the Conservatives for the Labour Party in 2022.

By Lucy Gilder, BBC Verify

“Since he [Rishi Sunak] claimed victory 16 days ago, there have been a staggering 2,400 small boat crossings,” Sir Keir Starmer claimed during Prime Minister’s Questions.

On 22 April 2024, Rishi Sunak held a press conference after the Safety of Rwanda Bill passed through the House of Commons.

Since this time 2,409 people have been detected crossing the Channel in small boats up to 6 May. So Sir Keir is correct.

The number of small boat crossings in this period is up 76% compared to the same time last year, when 1,366 people crossed between 22 April and 6 May 2023.

So far this year, 8,674 people have crossed the Channel.