That's all from us today.Please join us again tomorrow. David Cameron is in Iceland for a meeting of the Northern Future Forum, where all eyes will be on what other European leaders have to say about the UK's future in Europe and forthcoming referendum. Back in Westminster, the focus will again be on tax credits - as MPs debate a motion put forward by Labour MP Frank Field calling for the cuts to be staggered to allow employers to increase wages in line with the loss in lower tax credits. Meanwhile, Jeremy Corbyn and Shadow Business Secretary Angela Eagle will visit Tata Steel in Scunthorpe.

Image source, PA

This from the BBC's security correspondent Gordon Corera

The head of MI5 has said in a speech that he hopes the upcoming debate on intelligence powers will be a mature one and not one characterised by ill-informed accusations of mass surveillance. 

A draft bill updating the state's powers to intercept communications and carry out surveillance is expected next week. 

Andrew Parker was speaking at at the Lord Mayor of London's annual defence and security lecture. 

His part of a broader campaign by spies and police to make their case ahead of the new bill. He said that a growing proportion of communications by those involved in terrorism was now beyond the reach of MI5 due to new technology. 

This problem - which he described as that of 'going dark' - was, he said, an enormous challenge. Sifting through large amounts of data - such as phone records - and even hacking into computers was increasingly vital, he argued. 

But he also said he recognized the need for greater transparency. 

Image source, Reuters

This from the BBC's political correspondent Robin Brant.

The other 27 nations in the European Union are "pretty clear" about what reforms the UK wants, the Europe minister has said. 

David Lidington rejected criticism that Britain has been ambiguous and failed to put detail on the changes it wants in the run-up to the EU referendum - to be held before the end of 2017.

He told an audience in London he thinks officials are "pretty clear about what it is that we want" from the renegotiation process. The British government is focused on four areas of reform. 

Technical talks have been completed and David Cameron is expected to lay out more specifics about the reforms he wants in a letter to the President of the EU council Donald Tusk in a few weeks time. 

That letter will be made public.German Chancellor Angela Merkel is reportedly among those who've said the British government has not yet explained in any detail what it wants to achieve. 

This from the BBC's political correspondent Paul Rowley.

Three protesters arrested during last week's state visit to Britain of China's President Xi Jinping will not face further police action. The three were initially bailed for alleged breach of the peace and suspicion of conspiracy to commit threatening behaviour. But Scotland Yard have confirmed tonight there'll be "no further action". The Labour MP for Leeds North East, Fabian Hamilton, told the Commons on Monday that he was "deeply concerned" at the arrests, which he said led to their homes being searched while they were in police custody, and their computers and iPads seized. Their mobile phones were also confiscated on arrest. This evening the MP told the Commons that "all charges have been dropped".

At this week's Prime Minister's Questions, David Cameron and Jeremy Corbyn clashed over the government's tax credits plans. 

The Labour leader pressed the PM six times to guarantee nobody will be worse off as a result of cuts to tax credits. Mr Cameron defended the changes and said workers would benefit from other government policies including a higher minimum wage and free childcare as well as a stronger economy.

In other political developments:

• David Cameron has told some Eurosceptics campaigning for an EU exit they are wrong, ahead of a summit of northern leaders in Iceland where he will continue to make the case for EU reform 
• A review into the workings of Parliament triggered by government defeats in the House of Lords could be completed by Christmas
• Job advisers are set to be placed in food banks across the country, Work and Pensions Secretary Iain Duncan Smith has told MPs
• The UK business secretary Sajid Javid has called for an emergency EU meeting to discuss the crisis in the steel industry
• The PM has launched an independent "root and branch" review of children's homes in England.

Speaking in Iceland ahead of the meeting of the Northern Futures Forum, David Cameron has warned against those who are arguing for the UK to leave the EU and adopt a looser trade relationship similar to that which Norway has with the EU. The prime minister said Norway still had to pay as much into the EU as the UK, was bound by similar rules on migration, and had less influence over its decisions.

Here. courtesy of the BBC's Jack Evans, are some stats on Jeremy Corbyn's choices of subject for his PMQs appearances so far:

• 58% of the questions have been about tax credits
• Four have been about housing or housing costs, and two about the steel industry
• His crowdsourced questions have come from Marie, Steven, Paul, Claire, Gail, Angela, Kelly, Matthew, Frances, Emma, Lisette, John and Karen
• So far, there has been a lack of questions from Mr Corbyn on two of Ed Miliband’s big topics - the economy and foreign affairs
• In Mr Miliband's five years at the despatch box, the economy was his most asked-about topic, on 183 occasions

Shadow health secretary Heidi Alexander has accused the government of not providing enough clarity to junior doctors on the proposed changes to their contracts. 

During an opposition day debate on the issue in the Commons, she said junior doctors were the lifeblood of the NHS and that the vast majority already work nights and weekends. Yet, she argued, "everybody thinks they are going to lose out" under the new arrangements.

Referring to a morning she spent shadowing a junior doctor, she said:

Laura Kuenssberg
BBC political editor

Listen very carefully and you just might hear the sound of a third, yes a third, campaign joining the arguments about whether the UK should stay in, or run for the EU exit.

OK, it's not an official campaign, but its leader is already well known - our prime minister, who, until today has been hanging back from the fray.

The case - they want you to vote to stay in if they improve our relationship with the rest of the European Union. But if the next few months don't go their way, well, they might just ask you to leave. 

This unofficial campaign, run from No 10, may as well be called, "reform, or we might just cut and run".

Read more from Laura.