London's police have a message for the thousands of people expected to line the processional route at Friday's royal wedding: Have a great time, keep your belongings close and, if you get a chance, please give us a hand.
"We need you to be our eyes and ears," said Commander Christine Jones of London's Metropolitan Police, which will have 5,000 officers in central London to provide security for the wedding of Prince William and Kate Middleton. "If you see someone acting suspicious or strangely, bring it to the attention of our officers."
In addition to vigilant citizens, the security detail will include police with sniffer dogs, divers in the Thames, undercover "spotters," motorcycle escorts, specialist search officers and an armed detail - though most of the police will be on duty without weapons, as they usually are. In addition, the military will be present in a ceremonial role, with the bearskin-wearing Foot Guards lining the streets.
Ms. Jones said the police had been preparing for this operation since the royal engagement was announced last November. In recent weeks, police activity has stepped up, with regular searches of drains, sewers and mailboxes, as well as the unfamiliar sound of helicopters buzzing over central London.
It is unclear yet how many spectators will arrive to watch the procession as it makes its way from Buckingham Palace to Westminster Abbey, where the couple are to be married (Ms. Middleton and her family will leave from the nearby Goring Hotel, where they are spending the night.)
The crowd size will likely depend on the weather, and showers are forecast for Friday. In any event, large screens placed in Trafalgar Square and Hyde Park will broadcast the service, which begins at 11 a.m. (6 a.m. ET.)
Sixty-odd protesters have been flagged as likely to cause disruptions and have been banned from central London for the day. Muslims Against Crusades, a political group that had planned to protest the wedding, has cancelled its rally.
The threat level in Britain remains at "severe," unchanged from the end of January 2010.
Ms. Jones said British security services were also monitoring social media. "There is quite a lot of chatter on the Internet. The challenge is separating the wheat from the chaff," she said, adding that no specific threat had been identified.
The 1,900 wedding guests, including heads of state, royal families, pop stars and Prince William's colleagues from the RAF base in Wales where he works as a search-and-rescue pilot, will be required to go through security checks and provide identification before entering the church.