Decades of planning helped to ensure security at Queen’s funeral, says expert

Scale of operation surpasses 2012 Olympics as world leaders and hundreds of thousands of spectators attend event in London

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.