The success of the enormous security operation surrounding the Queen’s funeral followed decades of intricate planning and heightened public vigilance, a counter-terrorism expert has said. Royalty, world leaders and hundreds of thousands of members of the public were kept safe on Monday, amid heightened concerns over possible attacks. The scale surpassed the operation for the platinum jubilee weekend and the London 2012 Olympics, which saw up to 10,000 police officers on duty a day. Nick Aldworth, the former counter-terrorism policing national coordinator, said the plans for the Queen’s funeral had been discussed in minute detail for decades. “The success behind the scale of this enterprise is from the years of planning,” he told the Guardian. The UK public’s heightened awareness of possible terrorist acts, and their willingness to report suspicions, has also made central London an ideal venue for a large-scale event, he said. “London, because of what it has experienced and years of vigilance, is in many ways an ideal venue because the public are aware of possible dangers,” he said. The Metropolitan police deputy assistant commissioner Stuart Cundy said on Sunday that “nothing can compare” to the “hugely complex” task. The funeral was the “final and most complex phase” of the policing operation that took place after the death of the monarch, he said. It comes as the country’s terrorism threat level stands at “substantial”, meaning an attack is “likely”. Police and security services had expressed concern about the possibility of knife attacks, bombs being detonated, and all other possible terror threats or incidents. The security services were also involved in the funeral’s planning, identifying any potential threats, while the Centre for the Protection of National Infrastructure was responsible for providing expert advice to the director of MI5 and across government. More than 3,000 other officers from almost every force in the country were drafted in to help police in London. Armed police, motorbike escort riders, officers carrying out patrols on horseback, dog teams and the marine unit were among the specialist teams involved. Rooftop snipers were in place while the cortege was moving, accompanied by a helicopter escort anywhere outside the capital. So-called lone-actor terrorism, in particular knife attacks, are now considered the main threat. However, police guarding the new King and senior royals also have to consider the risks posed by people who are fixated with those in the public eye. Members of the public were urged to report any suspicious behaviour, with security experts describing potential terrorists among the crowds as people who would seem “blatantly out of place” and uninterested in ceremonial events. By Friday morning, more than 30 arrests, for a range of offences, had been made as part of the operation, Cundy said. Since then, a man has been charged with a public order offence and is due in court after an alleged disturbance by the Queen’s coffin in Westminster Hall. Another man has appeared in court facing allegations he sexually assaulted two women who were in the queue to attend the Queen’s lying in state. More than 22 miles (35km) of barriers in central London alone were put up to control crowds and keep key areas secure. About 2,300 police officers oversaw the Queen’s final journey from Westminster Abbey to Windsor Castle. Approximately 1,000 lined the route, alongside military personnel, from the abbey to Wellington Arch as the Queen’s coffin was carried from the service by gun carriage.