Security is high in London as leaders from around the world begin arriving ahead of Monday's funeral for Queen Elizabeth II.
Prime Minister Justin Trudeau lands later today as part of a Canadian delegation that includes Gov. Gen. Mary Simon and four former prime ministers.
Hundreds of thousands of members of the public are expected to travel to London for the funeral, as well as dozens of other world leaders including U.S. President Joe Biden.
Streets around the Palace of Westminster were blocked off with metal barricades today, with a large contingent of police from across the United Kingdom directing the crowd who had come to pay their respects to the queen.
A visiting professor at the University of Suffolk who studies crowd management says the security plan for the queen's funeral has been in development for decades.
G. Keith Still says the effort involves high levels of co-operation between agencies to manage elements that include VIP security, counterterrorism, crowd management, as well as the health and welfare of those who gather.