Here's a round-up of today's political developments:

• Labour renounced its support for the government's fiscal charter, in a U-turn performed by the leadership
• The campaign to keep Britain in the EU has been launched, with ex-M&S boss Lord Rose at the helm
• Boris Johnson joined the debate, saying the price of quitting the European Union is "lower than it's ever been" 
• In the Commons, Labour deputy leader Tom Watson gave a defiant response to calls for an apology for demanding that police investigate sex abuse claims against the late Lord Brittan
• Leading former judges and lawyers have criticised the government's "slow and narrow" response to the migrant crisis
• The coke ovens and blast furnace at the Redcar steelworks will close after no offers to buy them were received.

Labour has renounced its support for the government's fiscal charter, in a U-turn performed by the leadership.

Shadow chancellor John McDonnell had said the party would back the plans, which commit future governments to maintaining a budget surplus.

But he has now said Labour will oppose the charter in a vote on Wednesday, to underline its "anti-austerity" stance.

Chancellor George Osborne said Labour's economic policy had "lurched from chaos to incredibility".

More here.

Lord Brittan's brother, Sam has spoken to the BBC about whether Tom Watson should apologise for the way he made allegations about the former home secretary.

"I'm not going to make a long speech about him - he's not worth it," he said, but added: "I would have liked him to have applied for the stewardship of the Chiltern Hundreds." (this is a way for MPs to resign).

Asked if Mr Watson should apologise now he said: "He won't apologise to anyone, I mean he lives in the dirt and he can stay there."

Asked whether he will apologise to Lord Brittan's family, Tom Watson says: "I'm not entirely certain whether that would be productive."

He's asked whether he should step down as Labour deputy leader, and tells Channel 4: "Absolutely not." Does he think he's fit for office? "Of course I do," he replies.

Channel 4

Tom Watson has been speaking to Channel 4 News following his refusal to apologise for demanding that police investigate sex abuse claims against the late Lord Brittan.

He says there were "multiple allegations" against Lord Brittan and "I think I was right to try and make sure police and criminal justice system were adhering to guidelines".

He says he regrets using the emotive language he did in his public comments about Lord Brittan, and had apologised "for the distress it caused".

It's the first day back for MPs after the conference season, but there's been plenty going on outside Westminster today too:

• The campaign to keep Britain in the EU has been launched, with ex-M&S boss Lord Rose at the helm
• Boris Johnson joined the debate, saying the price of quitting the European Union is "lower than it's ever been" 
• In the Commons, Labour deputy leader Tom Watson gave a defiant response to calls for an apology for demanding that police investigate sex abuse claims against the late Lord Brittan
• Leading former judges and lawyers have criticised the government's "slow and narrow" response to the migrant crisis
• The coke ovens and blast furnace at the Redcar steelworks will close after no offers to buy them were received

More from Sir Nicholas Soames on Tom Watson's response to his call for an apology over the way he handled sex abuse allegations against Leon Brittan.

Sir Nicholas said Mr Watson's statement to MPs earlier was a "non-apology" and that his conduct was "completely unacceptable".

Labour's deputy leader "has become a sort of witch-finder general," Sir Nicholas told BBC Radio 5 Live.

"I agree with Tom Watson that cases of child abuse have got to be rooted out and have got to be dealt with," he added.

Some background to Tom Watson's comments in the Commons just now, and Conservative MPs' call for an apology.

The Crown Prosecution Service found in July 2013 that there was not enough evidence for a prosecution over the claim former Home Secretary Lord Brittan had raped a 19-year-old female student in 1967.

Mr Watson later called for a full review of all abuse allegations made against the peer.

Officers subsequently interviewed Lord Brittan, who had terminal cancer at the time, but no charges were brought.

Police have since said they would not have taken further action over the rape claim.

A former Conservative MP has told a court his reputation had been "trashed" by a national newspaper which alleged he breached parliamentary codes of conduct.

Tim Yeo, MP for South Suffolk 1983-2014, is suing The Sunday Times for libel over three articles from 2013.

The paper claimed he told reporters he could promote business concerns in return for cash, the High Court heard.

Mr Yeo's counsel said his client never said he could act as a "paid advocate".

Read the full story

The price of quitting the European Union is "lower than it's ever been", Boris Johnson has claimed.

Speaking in Japan, the London Mayor and Conservative MP refused to rule out spearheading the 'Out' campaign.

But he argued it was better for the UK to stay in a reformed EU, saying he backed David Cameron in his efforts to secure change ahead of the referendum.

Read the full story

Over in Westminster Hall, MPs are debating the legalisation of cannabis, following an online petition. You can watch it here, external.

Talking at the despatch box, Tom Watson says he understands that MPs feel "aggrieved that Leon Brittan was interviewed by the police and that they're angry with my use of language".

But he argues that when anyone is accused of such crimes the police have a duty to investigate "no matter who it is". He says it wasn't for him to judge the validity of the claims against Leon Brittan, as he defends his decision "to demand that the guidelines were adhered to".

Addressing comments made by PM David Cameron, who said the Labour MP, needed to "examine his conscience", he adds:

As he sits down, Conservative MPs can be heard shouting "shame".