'Ring Of Steel' security operation is in place in London today

London is today playing host to the biggest security operation in British history, as a 'ring of steel' has been thrown around the capital to protect the Queen's funeral.

Over 10,000 police officers are on the streets, with many drafted in from other parts of the UK to help the Metropolitan Police cover the event, while the roofs are lined with snipers ready to pick off potential threats.

Over 22 miles worth of barricades believed to be capable of stopping an explosives-laden truck have also been erected to prevent another potential angle of attack.

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Sniffer dogs keeping a nose out for potential placement of bombs have been out and about for days ahead of the funeral to ensure the safety of those attending.

Security guards on crowd control duty are also looking through the scores of people who have flooded London's streets to pay their respects to see if they can spot any with ill-intentions in mind.

The security operation for the Queen's funeral is even bigger than the policing effort involved in the 2012 Olympic Games.

With many of the leaders of the world's major nations in attendance at the Queen's funeral, tight security is all the more important.

Presidents, prime ministers, other heads of state and government, ambassadors and royals from around the world have all packed into London to attend the Queen's funeral.

Stuart Cundy, deputy assistant commissioner for the Metropolitan Police, said plans had been made for a 'truly immense operation of huge scale and complexity'.

He said: "There’s absolutely nothing that compares to our policing operation this week, and particularly on Monday for the state funeral.

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"This will be the single largest policing operation that the Met police has ever undertaken and I think is ever likely to undertake.

"Our contingency planning considers a whole range of different scenarios which includes everything from terror attacks to criminal activity to crowd surges and crushing."

The UK's terror threat level currently stands at 'substantial', meaning the chances of a terrorist attack are considered likely.

Security planners consider the main threat to be 'lone actor terrorism', individuals working alone to carry out a solo attack.

As part of security efforts, more than 2,000 police officers have been deployed to Windsor, where the Queen's body will be buried alongside that of her husband and a final private ceremony held for the royal family.

Drones were also considered to keep an eye on crowds in Windsor, though they are not allowed to fly over London as a no-fly zone has been enforced as part of the 'ring of steel'.