Monarchs and heads of state from countries around the world are expected to gather at Westminster Abbey for an official gathering on a scale rarely seen in recent decades. Mr Biden said on Friday he would attend, although the date has not yet been confirmed. Thousands of police officers will be on duty each day in the capital as crowds gather at Buckingham Palace and nearby Green Park to pay their respects and the force has urged people to “remain vigilant”. The Queen’s coffin will lie in state for several days before the event. Nick Aldworth, who led the national counter-terrorism arm of policing until his retirement in May 2019, said the events would take place in a “very different threat world” to the deaths of Diana, Princess of Wales and the Queen. Mother. “This will probably be the biggest policing and protection operation the UK has ever undertaken,” he told the Independent. “It only takes one car, one person to do something despicable and not only have you disrupted a constitutional event, but people are going to be injured and killed.” It comes months after a man armed with a crossbow reportedly traveled to Windsor Castle and threatened to kill the Queen. In 2017, a knife-wielding Islamic State supporter attempted a terrorist attack on Buckingham Palace, while two members of a neo-Nazi terror group were jailed for inciting attacks on Prince Harry in 2019. Owen West, a retired constable who specialized in public order, said police would work to ensure the public could “express their grief” safely. “It will focus on engagement and dialogue with those in the crowd, sharing information that could help them, keeping key routes clear,” he told the Independent. “Large crowds, these days, represent a potential threat of hostile action, so attention will be paid to risk assessment and measures to help protect the body of a crowd from that eventuality.” Roads have been closed to form secure barriers around busy locations, with barricades and other enemy vehicle mitigation measures. A major armed operation will take place for the Queen’s state funeral, including rooftop snipers guarding the procession and ground patrols. Scotland Yard said it had launched “well-tested policing plans” but has yet to confirm whether it will draw in officers from other parts of the country to bolster its ranks. A spokesman said requests under “mutual assistance” protocols would almost certainly be made in the coming days and that the National Police Coordination Center would organize officer movements, rest days, pay and accommodation arrangements for volunteer officers. A police officer looks at flowers outside Buckingham Palace following the death of Queen Elizabeth II on Thursday (PA) “During Operation London Bridge, it is expected that the total policing operation will last between 10 and 14 days, with support from forces across the UK and utilizing multiple policing capabilities,” a spokesman added. “Due to the nature of Operation London Bridge, which will involve a large number of foreign officials and large crowds, a wide range of police capabilities and specialties will be called upon to assist the security operation led by the Metropolitan Police.” Police leaders said the forces most affected by the arrangements have “long-term” plans to deal with the extra demand. A spokesman for the National Council of Police Chiefs added: “Police forces have business continuity plans in place to ensure they are ready to assist in this operation, in addition to continuing their core service to the public, keeping communities safe.” The intergovernmental procedures originally designed in the 1960s under the name Operation London Bridge have been updated and revised over the years. Mr Aldworth said he had first seen Operation London Bridge, then “a dusty ring on a shelf”, more than 20 years ago and that “current threat methodologies” had changed. He said he was not aware of a similar event taking place since the main terror threat to the UK became “lone actors”, often using vehicles and knives, rather than bombings and complex plots directed by terrorist groups. The former senior Metropolitan Police officer said crowds of people are a likely target, as well as high-profile memorial attendees. He recalled that while working at the 2012 London Olympics, mutual aid was implemented to “bring in almost every armed officer in the country” to guard international VIPs due to a lack of security officers. APTOPIX Queen of Japan of Britain Copyright 2022 The Associated Press. All rights reserved APTOPIX Queen of Japan of Britain Copyright 2022 The Associated Press. All rights reserved APTOPIX Las Vegas Britain Queen Copyright 2022 The Associated Press. All rights reserved. APTOPIX Australia Queen of Britain Copyright 2022 The Associated Press. All rights reserved APTOPIX Australia Queen of Britain Copyright 2022 The Associated Press. All rights reserved APTOPIX Japan Britain Queen Copyright 2022 The Associated Press. All rights reserved APTOPIX Queen of Britain Washington Copyright 2022 The Associated Press. All rights reserved. APTOPIX Las Vegas Britain Queen Copyright 2022 The Associated Press. All rights reserved. Queen of British Indonesia Copyright 2022 The Associated Press. All rights reserved. British Queen of South Korea Copyright 2022 The Associated Press. All rights reserved Queen Elizabeth II Elton John Copyright 2022 The Associated Press. All rights reserved. Queen of Australia Britain Copyright 2022 The Associated Press. All rights reserved Queen of Australia Britain AAP IMAGE British Queen of New Zealand NZME Queen of British South Korea Copyright 2022 The Associated Press. All rights reserved Mr Aldworth said that despite the expectation that bystanders would be well-meaning mourners, in tight crowds police “have no opportunity to distinguish between people” who get too close to the funeral procession or dignitaries. Ahead of the funeral, officers are being stationed outside key locations including major train stations, royal parks and outside royal residences in London. Roads around Buckingham Palace and busy areas are being closed as part of security arrangements and the public has been urged to remain vigilant. Deputy Assistant Commissioner Stuart Cuddy said: “This will be an extremely poignant time for the nation and I know people will want to pay tribute and celebrate the Queen’s dedication to public service. “Working closely with the City of London Police and British Transport Police, the Met will now co-ordinate and develop a comprehensive policing plan in London. This operation will be highly visible, particularly in Westminster and areas around Buckingham Palace and St James’s Park. “Many police officers will be on duty during this time to ensure the safety of those visiting London and to prevent any potential crime.”