Former attorney general Lord Goldsmith today described how he gave the "green light" for military action against Iraq just a month after expressing concerns about the legality of the war.
Giving evidence to the Iraq Inquiry, Lord Goldsmith said he personally presented a draft opinion to Tony Blair in January 2003 in which he raised questions about the legal basis for the use of force.
But the following month - after meeting US government lawyers in Washington - he returned to No 10 to tell Mr Blair's senior advisers they did not need specific authorisation from the United Nations.
"That was, on past precedent, sufficient to constitute the green light," he said.
Lord Goldsmith said he was asked to provide formal legal advice in December 2002 following the passing the previous month of United Nations Security Council resolution 1441, requiring Iraq to give up its supposed weapons of mass destruction.
Initially he had been concerned that there was an assumption in Whitehall that he was "optimistic" that the resolution did provide sufficient authorisation for military intervention, which was not his view.
On November 7 - on the eve of the resolution being passed - he met foreign secretary Jack Straw to warn him that he should not simply assume that it would be "all right on the night".
He said he wanted to make clear that "they should not take it for granted when it came that, when definitive legal advice was given, that we would be in a position to take military action".
In his initial five-page draft opinion, which he gave to Mr Blair on January 14, he warned that he still believed a further resolution was necessary, specifically authorising the use of force.
Mr Straw expressed concern that he should understand the "negotiating history" which had led to 1441 being passed, following intense negotiations in the UN with the French and Russians.
Lord Goldsmith said it was arranged that he should meet Sir Jeremy Greenstock, the British ambassador to the UN, and the US lawyers who were involved in the discussions.
On February 27, he returned to No 10 where he met Mr Blair's chief of staff, Jonathan Powell, and other senior advisers.
"My advice remained preliminary until February because I was conducting my inquiries and researches," he said.
"I told them that, in the light of the further inquiries I had made following my visit to the United States, following my discussions with Jeremy Greenstock, following my investigations of the negotiating history, I was of the view that a reasonable case could be made that a second resolution was not necessary and that was, on past precedent, sufficient to constitute a green light."
Lord Goldsmith told the inquiry he continued to believe that military action would be unlawful without a second Security Council resolution until February 2003.
He met Sir Jeremy in London on January 23, 2003 to get a first-hand account of what was said during the negotiations for Resolution 1441.
The ambassador told him that other permanent Security Council members, in particular France and Russia, had accepted that another resolution was not essential.
Lord Goldsmith said: "What Sir Jeremy was saying - this was the key issue - was they knew that what had happened was that the resolution which they had agreed meant that a second decision was not necessary.
"Therefore that the US and other countries, such as ourselves, could take military action without a decision."
But after this meeting the Attorney General wrote to Mr Blair to make it clear that he had not yet been persuaded that war would be legal without a further resolution, the inquiry heard.
"My provisional view at that stage was still the same," he said.
Inquiry committee member Baroness Usha Prashar asked him: "You were right in confirming it was your provisional view until February that a second resolution was actually necessary?"
Lord Goldsmith replied: "Yes."
He also told the inquiry he was "unhappy" about a letter Mr Straw wrote in January 2003, rejecting the opinion of his senior legal adviser, Sir Michael Wood, about the legality of any conflict.
Lord Goldsmith said: "I did not like, to be honest, the tone of what appeared to be a rebuke to a senior legal adviser for expressing his or her views."
He added: "It is the job of legal advisers to do their very best to get the law right and to advise their governments what the law requires of them."
Lord Goldsmith was asked whether he was concerned that his position flew in the face of the advice of Sir Michael and other experienced international law experts at the Foreign Office.
"I paid great attention to what their views were, of course, but ultimately I disagreed with the view that they took," he said.
But the former Attorney General, who did not attend Cabinet meetings at this time, suggested that he and other Government legal advisers should have been involved more closely in drawing up policy on Iraq.
"I think it would have been better if legal advisers are involved as the policy is being formulated rather than at the end, and I consistently said this to lawyers who were giving departmental advice," he said.
Lord Goldsmith said Attorney Generals should attend Cabinet discussions to "help to keep ministers on the straight and narrow".
However, he added: "My preferred route would have been different, but I have no reason to suggest that it would have reached a different conclusion because when advice was needed I gave it whether it was asked for or not."
Lord Goldsmith met senior US officials and lawyers - including national security adviser Condoleezza Rice and senior State Department legal adviser Will Taft - in Washington on February 10.
He said they had all been clear that President George Bush's one "red line" in the negotiations on 1441 was that they should not "concede a veto" to the French on military action - something which they were adamant had not happened.
"It was hard to believe that, given what I had been told about the one red line that President Bush had, that all these experienced lawyers and negotiators in the United States could actually have stumbled into doing the one thing they had been told must not happen," he said.
Two days later, in discussion with his legal assistant in London, he finally came to the conclusion that a second resolution was not necessary and he should revise his earlier draft opinion.
"We discussed this and I must have told her at this stage because it was my view 'I now do consider that there is a reasonable case'," he said.
He rejected the suggestion that he could have approached the French - who were the leading opponents of military action in the Security Council to discuss what they believed had been agreed in 1441.
"You cannot have the British Attorney General being seen to go to the French and ask them 'What do you think?' The message that would have given to Saddam Hussein about the degree of your commitment would have been huge," he said.
Lord Goldsmith said he was "overly cautious" in his initial advice to Mr Blair about the legality of the war.
He came down firmly on the view that the invasion would be lawful without a second resolution after being asked by the military to produce a "yes or no" verdict.
On March 7, 2003, the Attorney General presented Mr Blair with a 13-page legal opinion in which he said a "reasonable case" could be made for launching an attack without further Security Council support.
Ten days later he stated without reservation that resolution 1441 provided the necessary authority for the conflict.
Lord Goldsmith explained that this hardening of his advice was a response to the needs of military commanders wanting to ensure their troops would not face prosecution for taking part in the invasion.
He told the inquiry: "When I got the request from the Armed Services and from the Civil Service, 'We want the Attorney General to say he's of the opinion that it is or isn't lawful', then I very quickly saw that actually this wasn't satisfactory from their point of view.
"They deserved more. Our troops deserved more, our civil servants who might be on the line deserved more than my saying there was a reasonable case.
"So therefore it was important for me to come down clearly on one side of the argument or another, which is what I proceeded to do."
Lord Goldsmith said he had given his final legal opinion of March 17 following requests from the chief of the defence staff, Admiral Lord Boyce, on behalf on the armed forces, and the treasury solicitor Dame Juliet Wheldon, on behalf of the Civil Service, for clear "yes or no" advice.
Although he had attended a meeting with Mr Blair, deputy prime minister John Prescott, and Lord Boyce on March 11, he denied that Mr Blair had asked him for the new opinion.
"I don't recall the prime minister asking for that. No, definitely not," he said.
Lord Goldsmith explained how he came to a firm view that the conflict was legal.
He said: "The question 'Is it lawful or not?' only admits ultimately the answer yes or no. It could not be a little bit lawful.
"And, having reached the conclusion that the better view was that it was lawful, that was my view."
Cabinet ministers did not debate the legality of the conflict when Lord Goldsmith presented his advice to them on March 17, the inquiry heard.
The former Attorney General said: "I do recall telling Cabinet, 'Well, there's another point of view, but this is the conclusion that I've reached'.
"Then the discussion on the legality simply stopped and Cabinet then went on to discuss all the other issues...
"I was ready to answer questions and to deal with them. In the event, that debate did not take place."