Former SNP leader Alex Salmond asks the Speaker if there could be "unambiguous" guidance - and a cross-party motion to be passed - to ensure that the Wilson doctrine (that security services don't target MPs' communications) is re-established following the ruling earlier today. 

Read more of the background here.

Jeremy Corbyn used a question from Matthew - one of "3,500 submitted" to him on housing – to ask the prime minister about buying a home in London. 

David Cameron said “we are doing everything we can” to get councils to build more houses, and said he wanted to see starter homes in the capital in the £150,000 to £200,000 price range. 

And he asked the Labour leader to work together to “get London building, to get prices down”.  

Jeremy Corbyn uses one of 2,000 questions from voters about tax credits, when he quotes Kelly, a single mother who looks after a disabled child, who reckoned government changes would make her worse off. 

The prime minister said “obviously Kelly will benefit” with the National Living Wage which he said would mean a £20 a week pay rise next year, and she would also receive extra child care.  

The SNP's Marion Fellowes calls for loopholes in the child support regime to cover backdated payments. Mr Cameron says he will look into it and write to her. That is the final question of the session.

Mr Cameron takes a swipe at the unions, once again rejecting Unite's call for online voting in strike ballots, saying he doesn't know what's wrong with filling out a form.

Mr Cameron offers his condolences to the family Georgia Williams and says lessons will be learned.

Read more here

Will David Cameron extend free fares for pensioners to trams, asks Fleetwood's MP.

Mr Cameron says he suspects it is a decision for the local council.

MPs fall silent as ex-Tory minister Cheryl Gillan asks about a young constituent who is facing a decision by NICE on whether they will fund drugs for the treatment they need. Mr Cameron says drug companies should bring prices down.

As the PMQs exchanges continue there is another call to Labour MPs to back the government in tonight's fiscal charter vote from Mr Cameron.

Image source, Getty Images

David Cameron deals with a couple of straightforward questions from backbenchers - and then a tricky one from Labour's Kevin Brennan, who asks the PM when he knew about Lord Ashcroft's "non dom" status. "Someone is telling porkies," adds the Labour MP.

Mr Cameron advises the Labour MP not to take much notice of what is in Lord Ashcroft's recent book about the PM - and offers to lend Mr Brennan copy, adding that he was given a free one.

Mr Cameron provokes loud roars from MPs after saying the government will later be implementing a policy (the budget charter) that was "Labour policy a week ago". The PM is using every opportunity to exploit Labour's discomfort over John McDonnell's U-turn on the vote. 

Read more here.

"The UK has no policy to help Syrian refugees who have made it to Europe", says Angus Robertson to rising noise from MPs. He asks if the PM will learn the lessons of previous military actions.

Mr Cameron says he cannot remember a question with so many errors in it and he does not recognise the picture Mr Robertson paints of the situation in Afghanistan.

The SNP's leader at Westminster Angus Robertson asks a broad question about what lessons Mr Cameron has learned from failed military interventions in Afghanistan, Iraq and Libya.

Mr Cameron says it is "frustrating" what is happening in Syria and Afghanistan, but sometimes not intervening is worse that intervening.