Image source, PA

The latest estimate of the cost of renewing the UK's nuclear weapons system is £31bn, over the course of the 20-year procurement programme, plus a £10bn contingency fund. This compares with a previous estimate of £25bn. "The revised cost and schedule reflect the greater understanding we now have about the detailed design of the submarines and their manufacture" the review document says, external.

Mr Cameron gives an "absolute guarantee" that the size of the British Army will not drop below 82,000 in response to Conservative MP Richard Drax. Reducing it to this size was the "most painful part" of the last defence review, he says.

The government is to invest £85m a year by 2017/18 in the BBC's World Service, as part of attempts to expand the UK's "soft power" and "global reach", the defence review, external reveals.

The Daily Politics

In case you missed it earlier, here's Conservative MP Johnny Mercer, Labour's Wes Streeting and the SNP's Patrick Grady looking at the difference British warplanes could make.

Former Defence Minister Sir Gerald Howarth asks whether the rapid response "strike brigades" can be delivered using existing force numbers, and asks why they will take 10 years to deliver. Mr Cameron commits to them being ready "as soon as they can be".

George Osborne and Bill Gates are teaming up to fight malaria. 

A £1 billion fund will be used to fight the disease working alongside the Bill and Melinda Gates Foundation.

The announcement, external comes a few days before the Spending Review and is "part of a fundamental restructuring of Britain’s aid budget".

David Cameron says he will consider a request from Labour's Yvette Cooper for a separate debate on military action in Syria before the day of the vote. The PM says there will be a full day's debate followed by a vote. "Put it like this, I don't think we are going to be under spoken or under considered," he says.

Carole Walker
Political correspondent

The government is to reduce the number of civilians employed by the Ministry of Defence by almost 30% to 41,000 by the end of this Parliament as part of its plans set out in the Strategic Defence and Security Review.

The review also says the Ministry of Defence will sell off 30% of its land and buildings, some of which will be used for new homes.

The review confirms the commitment to replace the Trident nuclear weapon system.  It includes a new figure of the cost of four new successor submarines which it puts at £31bn plus a contingency of £10bn.

Senior defence sources said the government was not scrapping incremental pay rises but the review does say the MoD will phase out commitment bonuses as part of wider changes to its pay structure.

The SNP's Angus Robertson, whose party opposes the renewal of the UK's nuclear missiles, describes Trident as "a weapons system of mass destruction which can never be used". 

Responding to him, the PM says Scotland is getting more Typhoons and maritime vessels and is "punching above its weight" because it is part of the UK. He defends the decision in 2010 to scrap the RAF Nimrod project.

The SNP's Angus Robertson, who says his party is the "effective opposition", says voters and shipworkers are being "betrayed" by a reduction in the number of type 26 frigates promised under the review.

Defence committee chairman Julian Lewis says his committee will assess the review in detail and asks about armed forces pay and when the Commons will vote on the UK's nuclear weapons system. Mr Cameron says the "annual pay upgrade" remains and that a vote on Trident will take place "at the appropriate time".

And here's a pic of Angela Eagle, far left, pointing at her twin sister Maria, who is shadow defence secretary: 

In response to Jeremy Corbyn's request for a human rights adviser in every embassy, Mr Cameron says that he thinks that is the role of the ambassador - to provide advice along those lines. It sounds like the Conservative MPs are enjoying this session more than Labour MPs.

Mr Cameron says the UK will develop a new type of frigate for use at home - and which can be exported to other countries.

David Cameron goes on the offensive in his response to Jeremy Corbyn. "The longer he went on, the less he had to say," he says, going on to highlight reported statements by the Labour leader and shadow chancellor John McDonnell.

Labour leeder Jeremy Corbyn also asks David Cameron if he will commit to having a human rights adviser in every British embassy. There's a final question asking the PM to agree not to cut police budgets and Mr Corbyn finishes.