Scores of police carefully examined the large temporary media structures that have gone up near the venerable abbey in central London, which will offer standing room for the thousands of journalists expected to cover Friday's nuptials of Prince William and Kate Middleton. Police slid mini-cameras inside piles of scaffolding pipes to make sure no bombs were hidden.
Scotland Yard's cavalry arm put its ceremonial division, known as the Grey Escort, through its paces ahead of the royal wedding, and the military geared up for an overnight dress rehearsal involving hundreds of service personnel expected to line the procession route.
Streets in London were being sealed off so troops from London's Wellington and Hyde Park Barracks could participate in the pre-dawn rehearsal Wednesday morning.
Police plan to deploy around 5000 officers to police the royal wedding procession, but Assistant Commissioner Lynne Owens appealed to the public to be on guard amid fears that Irish or Islamist extremists could target the ceremony.
"We really need you to be our eyes and our ears," Owens said.
Tuesday was the last day the abbey was open to the public before closing for wedding rehearsals and preparations on Wednesday and Thursday. Dozens of tourists milling around the ancient building were asked to pause for a moment of reflection as a public prayer was offered for the upcoming royal marriage.
"Today we pray for all couples preparing for marriage, especially today we pray for His Royal Highness Prince William and Miss Catherine Middleton as they prepare for their great day on Friday," the Rev. Martin Hume said.
London has been bracing for a surge of visitors ahead of the wedding and on Tuesday those predictions were borne out as the Tower of London recorded its highest weekly number of visitors in 12 years. London and Partners spokeswoman Jacqueline French said the city could expect some 600,000 tourists specifically there for the royal wedding.
In London and across the country, Britons were getting ready to mark Friday with royal wedding parties. At the prime minister's Downing Street residence, just down the road from Westminster Abbey, children were baking cupcakes in anticipation of a wedding-themed charity bash. The children, joined by Prime Minister David Cameron's wife Samantha, posed for pictures as they finished their cupcakes, which were topped with Union Jack flags and edible stickers of the royal couple.
Overseas visitors need to be fed too: Britain's Foreign Secretary William Hague was to host a dinner on Thursday for all foreign dignitaries arriving to attend the wedding ceremony.
Those who couldn't make it sent their regards. Sailors from the HMS Iron Duke, the frigate on which Prince William served in 2008, addressed a video message to the prince and his fiancee that carried "best wishes for their wedding day and future life together."
At a prime spot along the wedding procession route, John Loughrey of London, a 56-year-old self-described "super-fan" of the late Princess Diana, was already camped out.
Wearing a shirt with William and Middleton's photo and the words: "Diana would be proud," Loughrey predicted that Friday would "be a fabulous, fantastic day."
Guen Murray, 76, had camped out for the 1981 royal wedding between Prince Charles and Lady Diana Spencer and was ready to do so again for their son William. She staked a place outside the abbey with her two daughters beginning at 8:00am.
Murray said the wedding was important to her because she "grew up during the war and learned to respect the royal family."
Weather forecasters have predicted a windy, cloudy and possibly wet Friday morning, but Murray didn't seem bothered.
Asked what she will do if it rains, she replied: "Well, get wet."
