But while that anger has been constant - his attitude on other aspects of the conflict appears to have evolved.

In particular, Mr Blair's position on the use of ground troops in Kosovo appears to have hardened as the weeks have passed.

What once seemed to be emphatically ruled out, is now being considered, at least in certain circumstances.

Blair: 'Moral outrage at ethnic cleansing'

Mr Blair's apparent shift in attitude may be fuelled by his sense of outrage, a belief that the people of Europe can not stand idly by in the face of a policy of ethnic cleansing.

"My generation never thought to see those scenes in Europe again," he told military leaders on a visit to Nato headquarters.

"Our task is very simple and our will in in seeing it through must be absolute and total."

A sense of "moral outrage" has been a common theme running through many of the prime minister's statements.

Just three days into the conflict, Mr Blair was describing the Yugoslav President, Slobodan Milosevic, as a "brutal dictator."

He has repeatedly insisted that the war is in a "just cause" and a "cause we will succeed in winning."

The statements may in part reflect Mr Blair's strong Christian convictions, but they have helped lead to the view that he is a 'hawk' in the conflict over Kosovo.

He has also shown a certain irritation with those not willing to completely share his analysis of the situation.

Early on in the conflict it seemed there was little doubt about the position of the British Government.

"There is no question of Nato ground forces being sent in unless it is to police an agreed political settlement," Mr Blair wrote in the Sun newspaper.

Even after sending extra troops to the region, the prime minister was adamant about what their job was to be, and what it was not.

"Let me make clear, for the avoidance of doubt," he told the House of Commons on 13 April. "They are being sent so that the UK can be in a position to play our proper role to ensure the refugees are able to return to Kosovo in safety."

Writing in Newsweek last week, he again acknowledged the need for ground troops to protect refugees and return them to their homes.

"But that is very different from fighting our way in. While we keep all options under review at all times, that is not our plan."

Mr Blair, like many of the Nato leaders, was clearly placing a great deal of faith in the war above the skies of Kosovo.

"We believe the air campaign will be successful," he told the BBC on 8 April.

The prime minister said immense damage was being done to President Milosevic's whole military infrastructure, his lines of communication, his supplies and "to his killing machine on the ground."

But critics of the use of an air campaign alone were continuing to make their voices heard.

In Britain this included the former BBC correspondent and independent MP, Martin Bell, the former European Community peace mediator Lord Owen, and the Liberal Democrat leader Paddy Ashdown.

There has been nothing so blatant as a U-turn, but slowly the government has altered the tone of its statements to leave more room for manoeuvre.

Ministers insisted that their plan all along had been for ground troops to go in, but only when the air campaign had created a "permissive environment."

In other words Nato troops would advance only when the Serbian forces had been weakened to the point where they could not offer effective resistance.

Ashdown: Has called for use of ground troops when moment is right

The prime minister gave what seemed a clear indication of this policy when he spoke to the House of Commons before leaving for Washington on 21 April.

"The difficulties of a land force invasion of Kosovo against an undegraded Serbian military machine are formidable, as they have been throughout," he conceded.

But significantly he added: "Milosevic does not have a veto on Nato action. All options are always kept under review."

But if Mr Blair has swung behind a more concerted use of ground troops in Kosovo, even after a lengthy air campaign, he could face an uphill struggle.