LONDON - New flags went up, cleaning crews scrubbed down, police checked for explosives and a handful of die-hard fans were already camping out. Welcome to Westminster Abbey, the ceremonial focus of Britain's royal wedding frenzy.

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.

To enhance security in the area, dozens of bailed anarchists - arrested in connection with alleged public order offenses during a chaotic protest against government cuts last month - have been barred from entering the Westminster area, for fear that they may cause trouble during the wedding, police said.

Workmen also delivered some surprising wedding floral decorations to the abbey. Instead of flowers, five men hoisted an 18-year-old potted maple tree inside. In all, six field maples and two hornbeams will form an "avenue of trees" lining the aisle leading up to the altar.

"These wonderful curved ceilings are supposed to reflect the branches of trees and that was what I thought of when I thought of having trees in the abbey," said florist Shane Connolly.

Streets in London were being sealed off so hundreds of troops from the city's Wellington and Hyde Park Barracks could participate in a pre-dawn dress rehearsal Wednesday morning involving those expected to line the procession route.

Scotland Yard's cavalry arm put its ceremonial division, known as the Grey Escort, through its paces Tuesday and the Band of the Royal Marines rehearsed.

Police plan to deploy around 5,000 officers to police the royal wedding procession, but Assistant Commissioner Lynne Owens appealed to the public Tuesday 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. 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.

Those who couldn't make it to London 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 8:00 a.m.

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."

Caroline Morrow, David Stringer, Sylvia Hui and Toby Goode contributed to this report.