Images of Britain's Prince William and his fiancee Kate Middleton are seen on a souvenir wedding mug in a photo released by Aynsley China in Stoke-On-Trent, England November 16, 2010.[Photo/Agencies]

Kate Middleton enters a room with her fiance, Britain's Prince William, to pose for a photograph in St. James's Palace, central London November 16, 2010.[Photo/Agencies]

A strong, stable marriage — one that lasts decades and produces heirs — could go a long way toward undoing the damage from the ugly squabbling and televised confessions of adultery that marred the final years of Charles and Diana's tortured marriage, which began on such a high note with their spectacular wedding in 1981.

"This is their chance to rejuvenate the dynasty," said Patrick Jephson, former private secretary to Princess Diana. "This is an opportunity for a welcome national celebration."

News of the engagement was greeted with enthusiasm — and relief — in Britain. Queen Elizabeth II and her husband, Prince Philip, said they were "absolutely delighted for them both," Buckingham Palace said. Prince Charles said he was "thrilled." Middleton's parents, Carole and Michael, also gushed.

"We all think he's wonderful. We're extremely fond of him," Michael Middleton said, standing near the couple's large house in the affluent Berkshire countryside.

Royal officials said that while Middleton is commonly known as Kate, her official name is Catherine Elizabeth. She will be named Queen Catherine if William, as expected, eventually takes the throne.

Middleton, in a royal blue dress that matched the engagement ring, said she had suffered when their relationship was in trouble — including a separation that left her unhappy — but that they had grown stronger in the years they've been together.

"You go through the good times, you go through the bad times," she said, promising to "learn quickly" in her new royal role.

William proposed during a vacation in Kenya last month and gave Middleton the oval blue sapphire surrounded by diamonds from the jeweler Garrard that Charles had given his mother.

William said he carried the ring around with him for weeks as he sought the right moment to pop the question. Middleton showed the ring with obvious pride.