The BBC's Norman Smith says the PM's speech on Europe was his "toughest" yet, with David Cameron making clear that he was "not bluffing" and could contemplate recommending the UK leave the European Union. As for the heckling, Norman Smith says it was a small protest but underlines the "tensions in the business community" about the CBI's position, with some unhappy the lobby group appeared to have set its face against leaving the EU.

The Irish Prime Minister Enda Kenny was asked about the corporate tax rate in Ireland which is lower than the UK. Mr Kenny defended the arrangement but added "we've been very conscious of this".

Image source, ITN

Irish Prime Minister Enda Kenny said he would be "sympathetic and supportive" towards any "achievable adjustments" Britain wanted from the European Union.

He believed the European Union has delivered healing to a broken and divided continent. He said the EU provided a way to amplify the voices of members. 

He said the Queen worked "exceptionally hard" to make her state visit to Ireland work and described it as a "historically significant moment of reconciliation".

The two people who briefly interrupted Mr Cameron's speech have been talking to Sky News. Asked how they got into the hall, they say they posed as businessmen after campaign group Vote Leave created a company in order to register for the event. They say it was "the most terrifying thing" they have ever done but was worthwhile to make the point. 

Image source, PA

The heckling during the PM's speech was directed at the CBI and their perceived support for the UK to remain within the EU. The hecklers were from a group known as 'Students for Britain', an offshoot of the Vote Leave campaign, which argues the UK would be better off outside the EU. The significance of their intervention would not have been lost on the PM, who is thought by many of his own MPs to want to stay in the European Union. 

Irish Prime Minister Enda Kenny is now addressing the CBI conference. This is pressure group Open Europe's interpretation of his message on the EU referendum. 

David Cameron also answered a series of questions about other issues, including energy, transport, planning, anti-corruption efforts, and technology. Trumpeting the progress that the UK is making on attracting foreign investors, he recalled a recent meeting with the head of Lego and says how pleased he was to receive a business card from him in the form of a Lego mini-figure. 

Image source, ITN

Speaking on prison reform Chancellor George Osborne said it was a chance to improve lives for the better. He said "yet we hardly do anything, we lock them up then let them out" and then they follow a life of crime. 

He said the prison estate needed to be modernised, as they were currently "soulless, bleak" places which were relics from the Victorian times. He confirmed the first prison to be sold will be Reading prison and would be sold as housing for young families.

David Cameron ends his speech with a plea to business to ensure equality of opportunity and not to "lock people out" because of "conscious or unconscious discrimination" on the basis of gender or ethnicity. This will help create a "fairer country and a more successful economy", insists.

Image source, ITN

Taking questions from the audience he was asked how he would protect London from the spending review.

He said within days of walking into the Treasury in 2010 he was advised to cancel Crossrail, the Crick Institute, and the Tate Modern extension but decided against it. 

David Cameron is asked whether he is confident that his negotiating objectives will eventually be enacted into law through treaty changes and how likely this is to happen before the end of 2017 - by when the referendum will be held. The PM says it will be "difficult and hard" but he believes that he can convince the EU's other 27 states to commit to irreversible and legally-binding commitments before the British public go to the polls. Quoting Ian Fleming, he goes on to to say that his goal is to create a "live and let live" European Union. 

The PM is taking questions from CBI members and journalists, including the BBC's James Landale, who asks whether the UK can get the changes on welfare - such as restrictions on in-work benefits for EU migrants - he wants. Mr Cameron says he is "deadly serious" about the negotiations and his specific requests. If the rest of Europe can show it has the flexibility to accommodate his demands, then the UK will stay in. If not, he says the UK will have to ask a "very profound question" about whether its EU membership still makes sense. 

David Cameron says the UK could clearly survive outside the EU, claiming it is a "duff answer" from the pro-EU campaign to suggest otherwise. That is interesting as it mimics rhetoric we have been hearing from Boris Johnson and others in recent weeks. But the PM says the big question is not whether the UK could survive but whether it would prosper and be in its long-term economic interest to leave the EU. 

David Cameron moves on to Europe, referring to the letter he will be sending to EU Council President Donald Tusk on Tuesday. He says he is not satisfied with the status quo and Europe needs to change.

If he gets the changes he wants, the PM says he will campaign "vigorously" to stay in the EU. If not, he says he will "rule nothing out" - a phrase we have heard a lot of in the past six months or so. The PM says he is "not firing the starting gun" on the referendum but wants to "debunk some myths". Among these he says is the belief that the so-called Norwegian model would work for the UK. 

George Osborne has said economic security is the "beating heart of the spending review". He said the debt is still high, meaning economic security is in danger as the UK will borrow £70 billion this year.

He said the government will use their mandate to bring the deficit down. He said a surplus is needed to help through the "tough times" adding the deficit could bring the country down and said we need to "hold our nerve".

He criticised those who oppose the current plans saying borrowing more didn't work before and won't work now. He said they were deliberating misleading the country. 

He confirmed he will set out more detail in the Spending Review later this month. 

The PM is interrupted by a heckler as he talks about the need to "finish the job" on reducing the deficit. He urges the heckler to listen rather than "making a fool of himself". The prime minister pauses for a minute, as it appears that the individual concerned is removed from the venue.