In what is being seen as the most significant split in British politics since the breakaway of the Social Democratic Party in the 1980s, a group of seven Labour MPs announced on Monday they have resigned.

Calling themselves the Independent Group, they appealed to MPs from all parties to “leave the old tribal politics behind”. They did not have to wait long.

Joan Ryan, the chair of the Labour Friends of Israel group, announced she would be the eighth MP to resign the next day, while three pro-European Conservatives - Anna Soubry, Sarah Wollaston and Heidi Allen - joined the group on Wednesday.

Here is everything we know so far about the new group:

Who are the MPs who have resigned?

Which MPs defected to form Change UK? Show all 12 1 /12 Which MPs defected to form Change UK? Which MPs defected to form Change UK? Change UK Details on the individual MPs are in the following photos Reuters Which MPs defected to form Change UK? Heidi Allen Anti-Brexit MP for South Cambridgeshire resigned from the Conservative party on February 20 PA Which MPs defected to form Change UK? Chuka Umunna MP for Streatham since 2010 and prominent People's Vote supporter PA Which MPs defected to form Change UK? Anna Soubry The prominent anti-Brexit MP for Broxtowe resigned from the Conservative party on February 20 PA Which MPs defected to form Change UK? Luciana Berger MP for Liverpool Wavertree since 2010, resigned from the Labour Party over bullying and anti-semitism PA Which MPs defected to form Change UK? Sarah Wollaston Anti-Brexit MP for Totnes resigned from the Conservative party on February 20 PA Which MPs defected to form Change UK? Joan Ryan MP for Enfield North resigned from the Labour party on February 19 citing its tolerance of a "culture of anti-Jewish racism" PA Which MPs defected to form Change UK? Ann Coffey MP for Stockport since 1992 Chris McAndrew / UK Parliament Which MPs defected to form Change UK? Gavin Shuker MP for Luton South since 2010 Getty Which MPs defected to form Change UK? Chris Leslie MP for Nottingham East since 2010 PA Which MPs defected to form Change UK? Mike Gapes MP for Ilford South since 1992 PA Which MPs defected to form Change UK? Angela Smith MP for Penistone and Stocksbridge since 2010

All the MPs campaigned for Remain during the referendum and have been vocal critics of Mr Corbyn's leadership.

Ms Ryan, the Enfield North MP, announced her resignation from Labour on Tuesday night.

Why have they split from Labour party?

The MPs have left the party due to Mr Corbyn’s stance on Brexit and his handling of allegations of antisemitism.

In the past they had routinely criticised the Labour leader and they have now said none of the current political parties in Westminster “are fit to provide the leadership and direction needed by our country”.

Mr Leslie, a former shadow chancellor, said Labour had been “hijacked by the machine politics of the hard left”, while Ms Berger said she had come to the “sickening” conclusion that the party is now “institutionally antisemitic”.

Ilford South MP Mr Gapes said he was “sickened that the Labour Party is now a racist, antisemitic party” and “furious that the Labour leadership is complicit in facilitating Brexit”.

The former Foreign Affairs Committee chairman said that a Labour government led by Mr Corbyn would “threaten our national security and international alliances”.

Stockport MP Ms Coffey, who has represented Labour in the Commons since 1992, said the party was “no longer a broad church”.

“Any criticism of the leadership is responded to with abuse and accusations of treachery,” she said: “Antisemitism is rife and tolerated.”

Luton South MP Mr Shuker said Labour was “riddled with antisemitism, it presents a threat to our national security and it’s perfectly content to enable the hard Tory Brexit that will directly and negatively affect people in Luton”.

Separately, Ms Ryan said she was "horrified, appalled and angered" by Labour's failure to tackle antisemitism, saying its leadership allowed "Jews to be abused with impunity".

Mr Corbyn said he was “disappointed” at their decision to leave.

“I am disappointed that these MPs have felt unable to continue to work together for the Labour policies that inspired millions at the last election and saw us increase our vote by the largest share since 1945,” said the Labour leader in a statement.

Why have some split from the Tory party?

Three MPs quit the Conservative benches over the PM's "disastrous" handling of Brexit.

Ms Soubry, MP for Broxstowe, fought back tears as she explained her decision, saying the battle for the soul of the Tory party was over and it had been taken over by "the right wing, the hardline anti-EU awkward squad".

Health committee chair Dr Wollaston said "the party, that was once the most trusted on the economy and business, is now marching us to the cliff-edge of a no-deal Brexit."

Ms Allen, the South Cambridgeshire MP, also said the party was turning a bling eye to the "suffering endured by the most vulnerable in society".

What does the Independent Group stand for?

In a statement of independence, setting out their values and approach, they promised to “pursue policies that are evidence-based, not led by ideology, taking a long-term perspective to the challenges of the 21st century in the national interest, rather than locked in the old politics of the 20th century in the parties’ interests”.

“As an Independent Group we aim to recognise the value of healthy debate, show tolerance towards different opinions and seek to reach across outdated divides and build consensus to tackle Britain’s problems,” the group pledged.

The Independent Group is due to hold its first formal meeting later this week.

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Will there be by-elections?

If an MP resigns from their party but wishes to continue on as an independent candidate there is no formal requirement for a by-election to be held.

Labour sources said the departing MPs should submit themselves for by-elections as they were elected on a Labour manifesto.

Pressed on the issue, Mr Leslie said “by-elections are absolutely not what is needed right now” due to the “national upheaval” that has been caused by Brexit.

A Downing Street source said that Conservative Associations in Ms Allen, Ms Soubry and Dr Wollaston's constituencies were now free to select new general election candidates, but said he was not aware of any central directive for them to do so.

He said that Number 10 does "not believe there is a great deal of merit" in Labour proposals for recall petitions for MPs who switch sides.

Who is their leader?

None of the MPs were introduced as the leader but Mr Umunna has been touted by most as a potential candidate.

However Ms Berger, who is eight months pregnant, took the lead during the press conference.

When asked if they had a leader, the MPs noted that meetings would be taking place this week to determine what individual roles people will take.

Are they an official party?

Not quite. As it stands they are just 11 independent MPs as they have not registered as a party.