The new commissioner of the Metropolitan Police has sworn allegiance to the King as he steps into the post amid unprecedented challenges.
Sir Mark Rowley, the former head of UK counter-terrorism policing, said he would be working to ensure the safety of crowds gathering to pay their respects to the Queen.
“I join the nation in sorrow at the death of her late majesty, the Queen, and share my condolences with the King and the royal family,” he added.
“Her late majesty’s unstinting public service, stoicism in times of turbulence and dedication to the people she served has shaped our nation immensely.”
The security operation around Elizabeth II’s lying in state at Westminster Hall and upcoming funeral is believed to be the biggest ever mounted by British police, with thousands of officers being pulled into London from across the country.
Sir Mark told Sky News he had been involved in planning for the Queen’s death during his previous role and had been working with the government and royal household.
“It's a massive challenge for the Metropolitan Police and for me personally, but we have been preparing for many, many years,” he said.
“I have a lot of trust and confidence in the fantastic police officers who are going to support this event and help make it safe.
“We will have a safe event but we will be putting thousands of officers into this because of the level of security required and the millions of people who want to pay their respects.”
Scotland Yard is also battling to rebuild public trust after a series of scandals and a decline into “special measures”, with protests continuing over the fatal shooting of an unarmed black man.
Sir Mark said: “In the next two weeks, I have two priorities. I will lead a Met that enables Londoners and visitors from all over the world to safely pay their respects to her late majesty, the Queen.
“Second, as we continue to police local communities, we will begin the journey of reform to renew policing by consent.
“Through my leadership, I am determined to bring more trust, less crime and high standards, and build trust and confidence in our police service once more.”
He took his formal oath and swore allegiance to the new King at an early-morning ceremony at New Scotland Yard on Monday, joined by deputy commissioner Dame Lynne Owens.
Under UK law, all serving police officers must swear to “well and truly serve the King in the office of constable, with fairness, integrity, diligence and impartiality, upholding fundamental human rights and according equal respect to all people”.
The oath continues: “I will, to the best of my power, cause the peace to be kept and preserved and prevent all offences against people and property; and that while I continue to hold the said office I will to the best of my skill and knowledge discharge all the duties thereof faithfully according to law.”
The mayor of London welcomed Sir Mark into his post, little over a week after an official review found he “constructively dismissed” Dame Cressida Dick earlier this year and had not followed due process.
Sadiq Khan said: “He is not only taking over as commissioner at a momentous time for our nation, but at a critical juncture in the history of the Metropolitan Police Service, which is facing some extremely difficult challenges.
“I look forward to supporting Sir Mark and working closely with him and the new home secretary to restore trust and confidence in the police, to ensure the Met can deliver a world-class service to all Londoners, and to build on the progress we have made in driving down violent crime across our city, bucking national trends, due to our investment and policies.”
