Princess Diana's brother, Earl Spencer, is locked in a battle royal with the House of Windsor over the role her sons should play, and the victor could decide the style of the monarchy in the new millennium.

Aftershocks from Spencer's bitter tribute to Diana at her funeral in Westminster Abbey were still reverberating on Monday, eight days after the princess's death.Many Britons echoed Saturday's applause for the earl for trying to protect her sons, Princes William and Harry, from the royal protocol and stiff upper lip said by some to have driven Diana to despair.

The 1,000-year-old monarchy will have to adapt to survive in a media-driven age where Diana's intuitive compassion struck an emotional chord with the public, commentators agreed.

"There must be changes all round. The applause that swept into the abbey symbolized the revolution the people demand," said the Sun, Britain's top-selling daily newspaper.

Others cautioned against change for change's sake, saying Queen Elizabeth's tardy reaction to the public mood may have saved the royal family from long-term damage.

There was also anger that Spencer, 33, had used a solemn occasion to vent his bitterness over the royals' treatment of his beloved sister. Charles was said to be incensed by the speech.

"Not since Mark Antony roused the Roman mob over Caesar's dead body has such a political funeral tribute been delivered," said respected constitutional expert and historian David Starkey.

"It was one of the cruelest speeches I have heard."

Spencer threw down the gauntlet when he vowed in his oration that Diana's "blood family" would ensure Princes William and Harry are not wrapped in the straitjacket of court tradition.

"The wounds within the royal family itself, and between the royal family and the country, have been reopened and made to bleed afresh," Starkey said.

Liberal Democrat leader Paddy Ashdown, reflecting on a momentous week, said the population was behaving more like citizens than subjects. Republicanism had reared its head as never before, royal experts said.

Prime Minister Tony Blair, who struck the right chord after Diana's death with his tribute to the "People's Princess," insisted the monarchy could adapt and said Charles would make a good king.

Spencer voiced support for the traditions of monarchy but made a fervent plea for William, 15, and Harry, 12, to be allowed to grow in freedom. Their souls should be allowed to "sing openly."

Many newspapers said they wondered how Spencer could help the princes from his home in South Africa, but they had little doubt battle lines had been drawn.

The Windsors won praise for leaving their ivory tower and learning to mourn in public - with the queen's televised tribute, bowed head before the coffin and flag at half staff.

But many mourners were fiercely protective of the young princes. "The only hope of saving the monarchy is to protect these boys from that dysfunctional family," Harry Hoyland said outside Kensington Palace.

"There's too much protocol, their family is too rigid. That's why they clashed with Diana," said Andrew Glowachi, 35, who took his son Adam, 4, to Kensington Palace to see the bouquets.

Historian Lord Blake urged the monarchy not to be bulldozed into revolutionary change by an avalanche of emotion.

"The royal family should carry on in their own cautious way," he said. "I do not think they should make sudden new departures."

The royal family became the House of Windsor during World War I, when its previous name, Saxe-Coburg and Gotha, sounded much too German.

But Matthew Engel, writing on the front page of the Guardian, had no doubt dark clouds were gathering on the horizon in a modern-day "Romeo and Juliet" battle between warring families.

"Spencer's address was not a eulogy but a battle cry. If Earl Spencer had gone a step further and called for immediate insurrection, they (the mourners) would have marched."