The new boss of the Metropolitan Police says preparations for the Queen's lying in state present a "massive challenge".
Sir Mark Rowley said the operation, which will involve thousands of officers, was something "we have been preparing for many, many years" as he started work as Commissioner of Britain's biggest police force on Monday.
He told Sky News: "It's a massive challenge for the Metropolitan Police and for me personally, but we have been preparing for many, many years.
