A round of up today's main political stories:

• David Cameron has defended the UK's business links with China as he said deals worth £40bn had been struck during President Xi Jinping's visit.  
• Tributes have poured in from across the political divide for Labour MP Michael Meacher, who has died aged 75 following a short illness
• David Cameron and Jeremy Corbyn clashed over plans to cut tax credits, with the PM warning the House of Lords not to block the policy
• Mr Corbyn accused him of "cutting people's ability to survive"
• EDF Energy reached an agreement with China General Nuclear Power Corporation for a nuclear power plant at Hinkley Point, Somerset
• A Conservative MP who broke parliamentary rules by leaking a committee report to a payday lender is to keep his job, the BBC understands
• MPs have said the government's flagship welfare-to-work programme deserves credit - but could do better
• The Met Police acted unlawfully by interviewing former Home Secretary Lord Brittan about rape allegations, a senior officer has told MPs

Peers have voted 242 to 190, majority 52, to scrap government plans to end onshore wind subsidies early despite claims it was a breach of the Salisbury Convention.

Asked by Labour MP David Winnick whether she was an acquaintance of Tom Watson - given that the MP had addressed his letter 'Dear Alison' - Alison Saunders says she had never met the MP until today. She dismisses claims that his letter had any bearing on her view of the case, saying her opinion had not changed at any stage of the process. 

US Vice-President Joe Biden has announced he will not run for the Democratic nomination in the 2016 White House race.

Making a surprise announcement in the White House Rose Garden, Mr Biden said there was not enough time left for him to mount a successful campaign.

He said it would be a mistake for Democrats to turn their backs on President Barack Obama's legacy.

Though he will not be a candidate, he said he "will not be silent".

More here.

Ross Hawkins
Political correspondent

Image source, Getty Images

Speaker John Bercow has joined more than 90 Conservative MPs demanding the government urgently rewrites the rules for funding schools in England.

In an unusual move, Mr Bercow has put his name to a letter intended to put pressure on Chancellor George Osborne ahead of the Spending Review.

Two Conservative former cabinet ministers and two ex-Labour cabinet ministers have also signed it.

The Department for Education said per-pupil funding was being protected.

Read more from Ross.

The Director of Public Prosecutions Alison Saunders is now giving evidence. She says the Brittan case was "not particularly complex" and suggests the police should have been able to make up its mind without having to refer to the Crown Prosecution Service. She says "at no time did the case" meet the level for charges to be brought - in terms of there being a reasonable prospect of a conviction and sufficient evidence. 

Mr Watson rejects claims by Conservative MP Tim Loughton that he was trying to "micromanage" this and other police investigations. Asked whether he was right to pursue the case in such a high-profile manner, he replies: "I think I did the right thing with the best of intentions".

IFS economist Andrew Hood looks at the chancellor's option.

Conservative MP Johnny Mercer implores the government to do "anything" it can to soften the blow of tax credits cuts.

Adding to the tributes to Michael Meacher, shadow chancellor John McDonnell has said the late MP "dedicated his life to the Labour Party and all that we stand for".

Commenting on the row over changes to tax credits, former Conservative Chancellor Kenneth Clarke told the BBC: "The Commons actually is the only chamber which decides tax, public spending, budget policy. That's been long established. The last time we had a constitutional crisis was over a hundred years ago, and it would absurd to repeat the 1911 crisis."

He added that if peers "start trying to reject £4bn worth of public expenditure savings, we are going to have a rather critical situation".

Labour MP Keith Vaz asks why Tom Watson allowed his office to be used for interviews relating to potential criminal behaviour, saying he is "not Sherlock Holmes". 

Mr Watson says he was not trying to "run" the investigation but was generally surprised by the number of accusations and the volume of material that had come to light following statement he made in the House of Commons. He goes on to defend his letter to  the Director of Public Prosecutions urging a review of the Brittan case, saying the language he used may have been "strong" but his intention was to make sure the "system was working properly". 

Pushed by MPs to make a more general apology for his role in the Brittan case, Tom Watson says he is very sorry for the "distress" caused to the late peer's family by how the investigation has unfolded in the full glare of the media but insists that he had no influence over the conduct of the probe and was merely trying to "amplify the voice of the complainant".

Keith Vaz starts by asking Tom Watson if he regrets using the phrase "close to evil" in respect to Lord Brittan. He says that he was repeating a form of words used by an alleged victim, although not the woman who made the rape allegation.

He says he regrets his use of language saying it was "emotive and unnecessary" and says he apologises sincerely for "any hurt" caused to Lady Brittan. 

Tom Watson begins his session by informing MPs that he has an ear infection and his hearing is slightly "impaired". Keith Vaz replies by joking that he hopes he and others won't "shout" at him. 

Labour leader Jeremy Corbyn has expressed his shock and sadness at the death of his "valued friend" Michael Meacher, MP for Oldham West and Royton who has died. He said Mr Meacher, who he first met in the 1970s and who support Mr Corbyn's leadership bid, "exemplified the very best" of socialist and labour traditions.