The Queen has officially welcomed the new aircraft carrier of the United Kingdom, HMS Queen Elizabeth, in a ceremony to commission it in the Royal Navy fleet.
The monarch boarded his boat of the same name in Portsmouth to see the white lieutenant of the Royal Navy on the ship for the first time.
Princess Anne, Secretary of Defense Gavin Williamson and First Lord of the Sea Admiral Sir Philip Jones also attended.
The ceremony took place on the deck of the giant carrier hangar £ 3.1bn.
HMS Queen Elizabeth and her sister ship HMS Prince of Wales are the most expensive in the history of the Royal Navy.
The navy initially estimated that both ships would cost £ 3.5bn to build, but the total figure was revised to £ 6.2bn.
Latest updates as HMS Queen Elizabeth enters service
About 3,700 guests attended the event, which came more than three years after the official naming ceremony of the ship in Rosyth when the Queen broke a bottle of whiskey in her helmet.
During the ceremony, the commissioning order was read, and the blue ensign, who has been flying from the ship until it is formally delivered to the Royal Navy, was replaced with White Ensign, proposed by Able Seaman, of 20 years old, Ellie Smith, from Hull.
Addressing the assembled guests and the ship's company, The Queen described the ship as "the most powerful and capable boat of all to raise the White Flag".
"At the forefront of these responsibilities will be the men and women of the Royal Navy, Royal Marines, with the support of the Army, the Royal Air Force and the coalition partners."
"As the daughter, wife and mother of naval officers, I recognize the unique demands that our nation asks of you and I will always value my special bond with HMS Queen Elizabeth, the company of your ship and your families, "he said.
Admiral Sir Philip Jones said: "We have been on a long, complicated but complicated journey until we reach this point and the launch of the ship is a key milestone.
" The objective of the great gray ship it is enormously large, flexible, capable and adaptable. "
As part of the ceremony, an 8-foot-long (2.44 m) cake replica of the ship was cut, as is traditional, was made by the member youngest boat company – Callum Hui, 17 – and the wife of the captain, Dr. Karen Kyd.
& # 39; A powerful symbol? & # 39;
By Jonathan Beale, Defense Correspondent
This is a great day for the Royal Navy. An opportunity to look to the future and, at least for a moment, forget about the recent defense cuts and the fears of even more.
After successfully completing its tests at sea, the HMS Queen Elizabeth will be put into service. For the first time, she will raise White Ensign, officially becoming a warship of the Royal Navy. But, this is another milestone, not the end of your trip.
Flight tests will begin next year and their first proper deployment with jets on board is not planned until 2021. It is also unclear how many of the new F35 aircraft will be carried.
Certainly less than the 36 for which it was built, with each jet costing around £ 100m. The Royal Navy believes that the airline, the first of two, will be a powerful symbol of British military power. But he is already struggling with limited resources.
Captain Jerry Kyd called the ceremony the "culmination of several years of true emotion."
He said: "Rosyth's first departure was only nine months ago, we have a long way.
" The first entry to Portsmouth was in the summer and here we are formally accepting the ship in His Majesty's fleet.
"So, it's at the top, it's the last milestone, many more to come, but very exciting and a very proud day."
The 900 foot long (280m) transporter can not currently deploy airplanes, but the F-35B Lightning fighters will make their first test flights from the carrier's deck next year, with 120 crew currently training in the US. UU
Preparations for the arrival of the flagship of the fleet and its 700 strong company carried more than 20,000 items, ranging from a human skull to marine mines, dredged from Portsmouth Harbor.
The Ministry of Defense said that specialized dredging vessels had eliminated 3.2 million cubic meters of sediment, equivalent to 1,280 Olympic swimming pools, during the dredging operation carried out to deepen the mouth of the port to allow the queen Isabel arrives at the naval base in Portsmouth.