It has taken seven years for Sir John Chilcot to publish the concluding report from his sprawling inquiry into the Iraq War following significant delays. The inquiry was set up in 2009 by the then prime minister Gordon Brown. At 2.6-million-words long, it covers the lead up to the March 2003 invasion and the years following.

More about the Chilcot report

After taking evidence from all those at the heart of the decision-making machine that led the country into war, including Prime Minister Tony Blair, and those responsible for carrying out the subsequent military occupation, Chilcot's report should help answer some of the biggest questions swirling around arguably the most controversial foreign policy decision of modern times.

Here, in brief, are some of those questions and answers.

Did Tony Blair commit Britain to a war in Iraq when he met George Bush in 2002 before he had consulted his cabinet and parliament?

Mr Blair's Note to President Bush of 28 July [2002] sought to persuade President Bush to use the UN to build a coalition for action by seeking a partnership between the UK and the US and setting out a framework for action.

The Note began:

"I will be with you, whatever. But this is the moment to assess bluntly the difficulties. The planning on this and the strategy are the toughest yet. This is not Kosovo. This is not Afghanistan. It is not even the Gulf War."

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The Inquiry considers that there should have been collective discussion by a Cabinet Committee or small group of Ministers on the basis of inter‑departmental advice agreed at a senior level between officials at a number of decision points which had a major impact on the development of UK policy before the invasion of Iraq [including] ... The position Mr Blair should adopt in his discussion with President Bush at Camp David on 5 and 6 September 2002. Mr Blair's long Note of 28 July, telling President Bush "I will be with you, whatever", was seen, before it was sent, only by No.10 officials. A copy was sent afterwards to Mr Straw, but not to Mr Hoon. While the Note was marked "Personal" (to signal that it should have a restricted circulation), it represented an extensive statement of the UK Government's position by the Prime Minister to the President of the United States. The Foreign and Defence Secretaries should certainly have been given an opportunity to comment on the draft in advance.

Was the intelligence upon which the case for war was made misrepresented to make it appear stronger than it was?

The statements prepared for, and used by, the UK Government in public from late 2001 onwards conveyed more certainty than the JIC [Joint Intelligence Committee] Assessments about Iraq's proscribed activities and the potential threat they posed.

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Intelligence and assessments made by the JIC about Iraq's capabilities and intent continued to be used to prepare briefing material to support Government statements in a way which conveyed certainty without acknowledging the limitations of the intelligence.

Did Tony Blair lie?

The JIC accepted ownership of the dossier and agreed its content. There is no evidence that intelligence was improperly included in the dossier or that No.10 improperly influenced the text... At issue are the judgements made by the JIC and how they and the intelligence were presented, including in Mr Blair's Foreword and in his statement to Parliament on 24 September 2002...

In the Foreword, Mr Blair stated that he believed the "assessed intelligence" had "established beyond doubt" that Saddam Hussein had "continued to produce chemical and biological weapons, that he continues in his efforts to develop nuclear weapons, and that he had been able to extend the range of his ballistic missile programme"... The Inquiry is not questioning Mr Blair's belief, which he consistently reiterated in his evidence to the Inquiry, or his legitimate role in advocating Government policy.

But the deliberate selection of a formulation which grounded the statement in what Mr Blair believed, rather than in the judgements which the JIC had actually reached in its assessment of the intelligence, indicates a distinction between his beliefs and the JIC's actual judgements. That is supported by the position taken by the JIC and No.10 officials at the time, and in the evidence offered to the Inquiry by some of those involved.

The assessed intelligence had not established beyond doubt that Saddam Hussein had continued to produce chemical and biological weapons. The Executive Summary of the dossier stated that the JIC judged that Iraq had "continued to produce chemical and biological agents". The main text of the dossier said that there had been "recent" production. It also stated that Iraq had the means to deliver chemical and biological weapons. It did not say that Iraq had continued to produce weapons. Nor had the assessed intelligence established beyond doubt that efforts to develop nuclear weapons continued.

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Cabinet was not misled on 17 March and the exchange of letters between the Attorney General's office and No.10 on 14 and 15 March did not constitute, as suggested to the Inquiry by Ms Short, a "side deal". Cabinet was, however, being asked to confirm the decision that the diplomatic process was at an end and that the House of Commons should be asked to endorse the use of military action to enforce Iraq's compliance. Given the gravity of this decision, Cabinet should have been made aware of the legal uncertainties.

Was the Iraq War legal?

The circumstances in which it was ultimately decided that there was a legal basis for UK participation were far from satisfactory... It was not until 13 March 2003 that Lord Goldsmith advised that there was, on balance, a secure legal basis for military action... In the letter of 14 March 2003 from Lord Goldsmith's office to No.10... Mr Blair was told that an essential ingredient of the legal basis was that he, himself, should be satisfied of the fact that Iraq was in breach of resolution 1441. In accordance with that advice, it was Mr Blair who decided that, so far as the UK was concerned, Iraq was and remained in breach of resolution 1441. Apart from No.10's response to the letter of 14 March, sent the following day, in terms that can only be described as perfunctory, no formal record was made of that decision and the precise grounds on which it was made remain unclear... The Charter of the United Nations vests responsibility for the maintenance of peace and security in the Security Council. The UK Government was claiming to act on behalf of the international community "to uphold the authority of the Security Council", knowing that it did not have a majority in the Security Council in support of its actions. In those circumstances, the UK's actions undermined the authority of the Security Council.

Did the British government fail to adequately plan for after the initial war against Saddam Hussein's regime was won?

UK planning and preparation for the post‑conflict phase of operations, which rested on the assumption that the UK would be able quickly to reduce its military presence in Iraq and deploy only a minimal number of civilians, were wholly inadequate... The Government, which lacked both clear Ministerial oversight of post‑conflict strategy, planning and preparation, and effective co‑ordination between government departments, failed to analyse or manage those risks adequately... Mr Blair, who recognised the significance of the post‑conflict phase, did not press President Bush for definite assurances about US plans, did not consider or seek advice on whether the absence of a satisfactory plan called for reassessment of the terms of the UK's engagement and did not make agreement on such a plan a condition of UK participation in military action.

Were British military personnel put in unnecessary danger because of a lack of sufficient resources and equipment?

Between 2003 and 2009, UK forces in Iraq faced gaps in some key capability areas, including protected mobility, Intelligence, Surveillance, Target Acquisition and Reconnaissance (ISTAR) and helicopter support. It was not sufficiently clear which person or department within the MOD had responsibility for identifying and articulating capability gaps... The MOD was slow in responding to the developing threat in Iraq from Improvised Explosive Devices (IEDs)... The decision to deploy troops to Afghanistan had a material impact on the availability of key capabilities for deployment to Iraq, particularly helicopters and ISTAR.