LONDON, United Kingdom — With former British Prime Minister Tony Blair’s testimony before the Iraq War inquiry now only days away, the nation watches in rapt suspense.

Known as the Chilcot inquiry after its chairman, Sir John Chilcot, the panel formed last summer to investigate the causes and conduct of the bitterly unpopular war has become Britain's daily drama fix.

Testimony this week will attack Blair’s most important position: that the war was legal. Elizabeth Wilmshurst, a top government lawyer who wrote at the time that the “unlawful use of force on such a scale amounts to the crime of aggression,” and backed her protest up by quitting, will appear in public for the first time since her resignation.

Her testimony is expected to further wound the former prime minister, already hurt by revelations that he privately committed Britain to war before consulting Parliament.

Adding to the drama of a once-powerful man about to be dragged to a public account, has been the sight of old allies, like Jack Straw, the justice secretary, distancing themselves from Blair.

In a country largely united in hatred of the Iraq war, Blair is the focus of venomous emotions. Some of his harshest critics will be present in the chamber when he appears Friday: relatives of British soldiers killed in what many of their countrymen view as a futile and unlawful conflict created by the United States.

Expecting mass demonstrations against Blair, Scotland Yard is planning to ring the venue with extra police.

A sense of spectacle pervades the government-appointed inquisition into the Iraq war. Held in a gray, modernist conference center a short stroll from the palatial, neo-Gothic parliament buildings, it is tempting to view the hearings as an attack on centuries of governmental secrecy and privilege by an implacable present.

Yet it is not so simple.

The inquisitors are not revolutionaries. They are titled members of the establishment, all with ties to government. Four of them are knights and one a baroness. Chilcot himself is a career diplomat and former top civil servant. There is the feeling in some quarters that Britain has been here before.

“There have already been four inquiries into the war,” said Steve Kettell, associate professor of politics and international studies at Warwick University, and a founder and co-editor of the journal British Politics. “There’s a huge body of opinion that all the others were a whitewash.”

The most dramatic of these was the Hutton inquiry into the death of David Kelly, a defense department biological-warfare expert. Kelly was unmasked as the source for a news report suggesting the government had knowingly exaggerated the threat posed by Saddam Hussein. If it had turned out, as the report implied, that Blair had deliberately misled the House of Commons, he would have been forced to resign.

Kelly was therefore a crucial link in a chain of potentially ruinous allegations against Blair. When the scientist was found dead in the woods near his Oxfordshire home in July 2003, reportedly driven to suicide by official harassment, the government was forced to set up the Hutton inquiry.

Lord Hutton, a high-court judge, exonerated the government, raising a howl of disbelief in the national press. The magisterial Sunday Times depicted the scholarly judge as the three wise monkeys, who hear no evil, see no evil and speak no evil.

“The same criticism could now be made of the Chilcot inquiry,” Kettell said — that it is an establishment panel not likely to pillory a former prime minister.

But it may have no choice. Key members of Blair’s cabinet have appeared at the witness table and been pressed about explosive revelations — for example, that Blair assured U.S. President George W. Bush, in private letters, that America could count on Britain.

Much hangs on the issue of legality. Blair’s detractors insist the conflict was illegal. Lord Goldsmith, Blair’s attorney general, appears to have given conflicting opinions, changing his mind to support the war only at the last minute.

Sir Michael Wood, formerly the Foreign Office’s most senior lawyer, told the inquiry Tuesday that Jack Straw, foreign secretary at the time of the war, had called Wood's legal objections "dogmatic," and insisted that international law was "pretty vague." Wood said he strongly disagreed with Straw's opinion.

Popular anger has been fueled by the belief of many Britons that Blair was Bush’s “poodle” — ready to go to war in return for America’s favor. So virulent was public feeling against Bush that central London was virtually shut down by the security arrangements for his 2003 state visit.

As Blair’s hour approaches, London police are again preparing for mass protests.

“There’s a huge upwelling of emotion,” Kettell said, “and the sense is that the people will never have a catharsis until the government is held responsible.”