But politics intruded on Friday's royal nuptials, with Britain withdrawing its invitation to Syria's ambassador to condemn the violent crackdown on protesters there that has left hundreds dead.
The rehearsal - the second in as many days - came as /*Middleton*/ and /*Prince William*/ released a message in their wedding program, saying they were deeply touched by the outpouring of affection toward them.
"We are both so delighted that you are able to join us in celebrating what we hope will be one of the happiest days of our lives," they wrote. "The affection shown to us by so many people during our engagement has been incredibly moving, and has touched us both deeply."
They also released a new photograph taken by celebrity photographer Mario Testino - a warm black-and-white image of a comforting snuggle.
Friday's wedding will offer pomp and circumstance on grand scale, with 1,900 invited guests, royal carriages and mounted troops of the Household Calvary. Rows of bold red, white and blue Union Jacks have been unfurled and street cleaners have scrubbed the pavement.
Thousands of people are expected along the parade route Friday, a snaking path less than a mile (two kilometers) from Westminster Abbey to Buckingham Palace, where the new royal couple will appear on the balcony for a kiss watched by millions around the world.
Westminster Abbey itself has been transformed into a blooming forest, with six field maples and two hornbeams lining the aisle leading up to the altar. Dozens of die-hard fans were already camped out in tents and sleeping bags near the iconic landmark.
The wedding presents a security challenge for the 5,000 police officers on duty, who will be on the lookout for Irish dissident terrorists, Muslim extremists, anti-monarchists, protesters and hooligans who might blight the royal spectacle.
A wide range of police will be on patrol: officers on motorcycles, escort specialists, dog handlers, search officers, mounted police, protection officers and firearms units.
Scotland Yard Police Commander Christine Jones said there has been no new terror threat but considerable Internet chatter. "Our operation has been meticulously planned, and we have thought through and planned for a huge range of contingencies," she said.
But it wouldn't be a wedding without a tussle over the guest list. Britain revoked a royal wedding invitation to Syrian Ambassador Sami Khiyami because of violent attacks on protesters by the regime there.
More than 450 people have been killed since last month in the uprising against President Bashar Assad's authoritarian regime, with 120 dead over the weekend, according to the U.N.
Royal families from Bahrain, Bhutan, Brunei, Kuwait, Lesotho, Oman, Qatar, Saudi Arabia and Swaziland have been invited, prompting the anti-monarchy Republic group to call the guest list "a Who's Who of tyrants and their cronies."
Critics had questioned why there was room for despots in the Abbey while former British Prime Ministers Gordon Brown and Tony Blair, both from the Labour Party, were omitted.
Prime Minister David Cameron said the event would be a moment of celebration amid Britain's tough period of austerity measures. His coalition government is carrying out 81 billion pounds ($135 million) worth of spending cuts through 2015, which are expected to cut hundreds of thousands of government jobs and sharply hike tuition fees.
The wedding would bring "happiness and joy and light relief after some difficult times," Cameron told Katie Couric on CBS.
"I think British people ... we feel very deeply about the monarchy and the institution, so it's that mixture of the good looking prince and the beautiful princess, but it's so much more than that," he said. "It's this institution that's helped bind the country together. And it's got this amazing history that goes way, way back."
Other wedding details began to emerge. The wedding program showed that Middleton will not promise to "obey" her new husband in her vows but instead to "love, comfort, honor and keep" him.
Middleton will walk up the aisle at the Abbey to the sounds of "I was glad," the anthem setting of Psalm 122 composed by Sir Charles Hubert Hastings Parry for the coronation of King Edward VII in 1902. The anthem was also sung at the wedding of William's parents, Prince Charles and the late Princess Diana.
The hymns - "Guide me, O thou great redeemer," "Love divine, all loves excelling" and "Jerusalem" - are standards at Church of England marriage ceremonies.
"Guide me, O thou great redeemer" was also the final hymn at Princess Diana's funeral in Westminster Abbey in 1997.
The newlyweds will leave to the march "Crown Imperial" by William Walton, which also figured in Charles and Diana's wedding.
A spokesman at St. James' Palace said Middleton was familiar with classical music but had "a lot of input" from Prince Charles.
"They spent a a lot of time listening to the music together on iPods," said the royal functionary, speaking on condition of anonymity.
But as wedding excitement heated up, the weather in London started cooling down. Royal wedding fans may want to pack extra umbrellas, as forecasters are predicting it might rain.
The Meteorological Office says the day will start off relatively gray and dry with low clouds across London. Some sunny spells are expected in the morning but the chance of showers will rise to 30 percent around noon, the time when William and Kate will emerge from the Abbey a married couple.
