Here's a round-up of the day's events so far:

• UKIP leadership hopeful Steven Woolfe says he is recovering in hospital after a reported fight at a meeting of the party's MEPs
• UKIP sources said "punches were exchanged" at a party meeting and Mr Woolfe banged his head, following a row over whether Mr Woolfe had been talking to the Conservative Party
• Dame Rosie Winterton has been replaced by Nick Brown as Labour chief whip and Diane Abbott becomes shadow home secretary as leader Jeremy Corbyn begins his shadow cabinet reshuffle
• Horizontal fracking can go ahead, the government has said, in a landmark ruling for the UK shale gas industry

Some more Labour shadow cabinet appointments have been announced.

• Diane Abbott becomes shadow home secretary
• Baroness Chakrabarti is shadow attorney general
• Jo Stevens has been appointed shadow secretary of state for Wales
• Sarah Champion is shadow women and equalities minister

Image source, bb

UKIP donor Arron Banks has said trouble in the party is down to "Tory troublemakers and fifth columnists" and declared: "If Neil Hamilton and Douglas Carswell remain in the party, and the NEC (UKIP's ruling body) decide that Steven Woolfe cannot run for leader, I will be leaving UKIP."

In a statement, Mr Banks said: "Firstly, I was shocked at the events that unfolded today - it goes without saying that I wish Steven best wishes and hope he recovers soon.

"I am however utterly disgusted to see Neil Hamilton touring the newsrooms this afternoon, spewing his bile before anyone knew if Steven was going to be OK. He truly is a creature from the gutter who will do anything to get his mug on our screens. 

"Tonight I am calling for the immediate suspension of the NEC. Elections need to be held for both a new leader of the party as well as the NEC."

BBC News Channel

Matthew Goodwin, professor of politics at the University of Kent, looks at the future of UKIP.

"There is room for a 10% to 15% party like UKIP," he says, meaning a party that records that level of support in the polls. However, recent events tell the voters the party is divided "and voters don't like divided parties".

But he thinks that "Theresa May is a formidable opponent for UKIP, much more so than David Cameron" who had a more "socially liberal" form of conservatism.

And Prof Goodwin says Nigel Farage has been profoundly influential, despite never winning a seat in the Commons.

"Most of his arguments now have been absorbed by the mainstream political parties," he says.

Radio 4 PM programme

Former UKIP Treasurer and prominent party donor Stuart Wheeler says the "bust-up" involving Steven Wolfe is not good for the party's image but is not unique.   

Mr Wheeler tells Eddie Mair he is not trying to defend the situation, which was "not desirable".

BBC News Channel

BBC political correspondent Iain Watson says Dame Rosie Winterton was seen by many as "a bulwark against attempts to deselect" MPs who have criticised Jeremy Corbyn.

However, her replacement Nick Brown is not a "classic Corbynista", having been close to former leader and PM Gordon Brown.

His appointment could be a sign that Mr Corbyn is reaching out to Labour MPs to try to heal divisions.

However, Iain adds, some MPs may still be worried that Dame Rosie has gone "and not of her own volition".  

Image source, AFP/GETTY IMAGES

We've just heard Nick Brown has replaced Dame Rosie Winterton as chief whip, but two other departures have already been announced.

Andy Burnhamsaid in his speech to the Labour conference that he would be stepping down as shadow home secretary to focus on the 2017 election for Manchester metro mayor. A former leadership contender, he has served in frontline Labour politics for a decade.

Kelvin Hopkins will be returning to the backbenches after four months as shadow culture secretary. He said at a fringe meeting of the Campaign for Labour Party Democracy in September that he had told Jeremy Corbyn he wanted to leave the front bench in the reshuffle.

Image source, PA

Labour's new chief whip, Nick Brown, served in the post from 2008 to 2010, when then-leader Ed Miliband asked him to stand aside.

Dame Rosie Winterton replaced him, having been the only MP to enter the ballot to become the next chief whip, who is responsible for party discipline.

Nick Brown was seen as an ally of former Labour Prime Minister Gordon Brown. Dame Rosie is a former minister and previously an adviser to John Prescott.

Image source, Labour Party

Image source, PA

UKIP did not deny Mike Hookem was the MEP who left the room with Steven Woolfe.

It followed heated verbal exchanges among MEPs during a meeting in the European Parliament.

The spokesman told the BBC that the events that followed were not witnessed by MEPs.

BBC News Channel

The BBC's Damian Grammaticas in Brussels says the meeting, in a room in the European Parliament in Strasbourg, was attended by UKIP MEPs only.

According to accounts from some of those present, Steven Woolfe's positive comments about the Conservative Party were raised and there was a "quite heated" exchange.

Some sources say Steven Woolfe "may have hit his head somehow against a railing or a wall" after being punched outside the meeting.

BBC News Channel

Former UKIP leadership contender Lisa Duffy tells BBC News: "It does appear that all is going to be well with Steven and for that we're all very, very grateful."

She says she has witnessed "many heated discussions" within UKIP but not one in which punches were exchaged, calling the incident in Strasbourg "deeply distressing".

She claims the party is going through "challenging times" following the resignation of Diance James and her message to UKIP members is: "Everyone please stay calm. There is a lot for us to do. We need to get a good leader in place."

Ms Duffy, who ran against Ms James and others for the leadership over the summer, says she has not yet decided to run in the current contest but is "certainly not ruling that out"

However, she adds:

Labour MP Nick Brown has been appointed as the party's chief whip, replacing Dame Rosie Winterton.

Leader Jeremy Corbyn said: "I welcome Nick's agreement to serve as chief whip to the parliamentary Labour party.

"I would like to pay tribute to Rosie Winterton for her six years' exceptional service as chief whip. She has played an outstanding role in her support for me as leader and for the Labour Party as a whole."

Commenting on his appointment Mr Brown, a former minister, said: "Jeremy Corbyn has asked me to serve as chief whip to the parliamentary Labour Party and I have accepted. I hope that I can bring experience and play a constructive role in providing the strongest possible opposition to this Tory government."

BBC News Channel

BBC political correspondent Tom Bateman says this morning's meeting of UKIP MEPs followed Steven Woolfe's recent praise for Theresa May's premiership and an admission he had "flirted with the idea" of joining the Conservatives but decided to stick with UKIP. This led to "real anger" among some UKIP MEPs, Tom says.

"It was described, rather sadly and ironically, as a clear the air meeting. Of course it turned out to be anything but.

"We are told that Mr Woolfe had left the room to be followed by another MEP taking his jacket off and there was an exchange of punches outside."

Mr Woolfe carried on with his day, attending a session of the European Parliament, which he left early, and later collapsed.