Massive security operation underway ahead of funeral

Ahead of the Queen's funeral on Monday, the most complex security operation London has ever seen is in progress.

Currently the Queen is lying in state, with thousands of people queuing on the streets to view the coffin and laying tributes around the city. For the funeral, royal families and heads of state from around the world will be in London.

The funeral will take place at Westminster Abbey, which does not have a permanent security perimeter.

All of this is a target for those wishing to do harm.

MI5 and GCHQ are working with counter-terrorism police. Reinforcements have come in from around the country to work with the Metropolitan Police. There are also military personnel and civilian stewards.

Police are asking the public to stay vigilant and report anything that does not feel right.

MI5 is watching for changes of behaviour in "subjects of interest". And armed police officers have been seen with binoculars in Westminster. Dogs are passing through the crowds to sniff out explosives and firearms.

The Met's Deputy Assistant Commissioner Stuart Cundy said: "At every event that we police in London, we are considering the threat from terrorism, the threat from crime, looking after people at the same time."

"So whilst it is a unique event we are well-versed, officers are well trained and also experienced at policing such large events."

The funeral has been compared to other large events to have taken place in London. It differs to the Olympics in that in 2012, people were in venues where they had to pass through security checkpoints. With the lying-in-state, the checkpoint is at the entrance to Westminster Hall, with people being in the queue for hours before then.

The threat has also changed over the years, with lone actor actors becoming more commonplace.

There will also be high-profile visitors including kings and queens and prime ministers and presidents from around the world, including US president Joe Biden and president of Israel Isaac Herzog.