Jeremy Corbyn is to undertake a wholesale review of Labour Party policy after embarrassing contradictions appeared on welfare and Europe this week with his senior spokesmen.

The announcement came as the new Labour leader took a novel approach to questioning David Cameron in the Commons, repeating questions emailed in from voters, which covered tax credits, housing and mental health.

Labour HQ made clear this was an attempt by Mr Corbyn to take a “more adult” approach to PMQs and “bring an end to Punch and Judy politics”.

It also sought to defuse the row over the Labour leader not singing the national anthem at a service in St Paul’s Cathedral to mark the 75th anniversary of the Battle of Britain.

After Mr Corbyn insisted he was showing respect at the service and pledged to take a “full part” in similar future events, a party spokesman had to intervene to underline this meant “singing the national anthem”.

As political parties prepare to mark the anniversary of the Scottish independence referendum, sources confirmed Mr Corbyn would not now be coming to Edinburgh this week as had been previously suggested.

Sources said “diary commitments” meant there had been a change of plan; a visit next week was possible.

After Hillary Benn, the Shadow Foreign Secretary, made clear Labour would campaign to stay in the EU, Mr Corbyn told MPs his party could not give the Prime Minister a “blank cheque” and might campaign to pull out.

When the Labour leader used a speech to the TUC conference to say his party would scrap the Conservative Government’s benefits cap, Owen Smith, the Shadow Work and Pensions Secretary, later stressed party policy was to support it but not endorse the move to cut the cap from £26,000 a year to £23,000.

Asked if it was tenable for a party leader not to support party policy, a Labour spokeswoman replied: “We’ve just had an election defeat and we have a new leader. Obviously, there will be lots of policy reviews going on and he will be listening to the Shadow Cabinet and decisions will be made as we go forward.”

In Mr Corbyn’s first appearance at the Commons dispatch box, he made clear he wanted to change the tone and content of PMQs, making it “less theatrical”. He revealed he had had 40,000 suggested questions from the public but had to choose just six to ask.

Mr Cameron said he welcomed the change in tone, telling his Labour adversary "no-one would be more delighted than me" if PMQs could become a "genuine exercise in asking questions and answering questions".

The SNP’s Mhairi Black tweeted: "Tories sniggering every time Corbyn mentions a member of the public's name. At least they are real people, unlike those the DWP made up."

In a separate exchange with the DUP’s Nigel Dodds, the PM made clear John McDonnell, the new Shadow Chancellor, should be "ashamed" of comments he made in 2003, suggesting Irish republican terrorists should be honoured.

Mr McDonnell is due to appear on BBC’s Question Time tonight; Alex Salmond, the former First Minister, is also set to be on the programme.

Meantime, Mr Corbyn dismissed as a "very, very minor incident" a scuffle outside his home, which left a cameraman in hospital. The party leader insisted "nobody was hurt" and that it was not his responsibility if a camera had fallen to the ground.

As Labour suffers from a lack of organisation following Mr Corbyn’s leadership election, one senior Tory source suggested Christmas had come early for the Conservatives. He told The Herald: “What we have to work out is - how do we keep Jeremy as Labour leader for as long as possible?”