The Queen will formally name the Royal Navy's biggest ever ship today, with whisky replacing the more traditional champagne at the ceremony.
She will smash a bottle of Islay malt whisky against the HMS Queen Elizabeth at the event at Rosyth Dockyard in Fife, where the 65,000-tonne aircraft carrier has been assembled and fitted out.
The Queen will be accompanied by the Duke of Edinburgh at the naming ceremony, a naval tradition dating back thousands of years which combines a celebration and a solemn blessing.
Other high-profile dignitaries including Labour leader Ed Miliband and First Minister Alex Salmond, along with his Second World War naval veteran father Robert, 92, will also attend the ceremony.
The naming of the warship comes five years after the first metal was cut on the vessel and 33 months after the first section entered the dry dock at Rosyth to begin being put together.
The ship and a second vessel, the under-construction HMS Prince of Wales, are the largest warships ever built for the Royal Navy.
Mr Miliband said: "Today we celebrate the skills and talents of the men and women who worked on the HMS Queen Elizabeth.
"This is the biggest warship ever built in the United Kingdom. Assembled here in Scotland, but built in six yards around the United Kingdom. From Glasgow to Birkenhead, Fife to Portsmouth, this contract has provided work to thousands of people across the country and made the best use of the skills and talents of the people who work in our yards. It is a visible reminder of what we can achieve when we work together across the United Kingdom.
In pictures: The world's biggest aircraft carriers
In pictures: The world's biggest aircraft carriers
1/10 The world's biggest aircraft carriers
Last year Japan unveiled a new $1.2bn warship, its largest since the Second World War
2/10 The world's biggest aircraft carriers
HMS Queen Elizabeth, due to be commissioned in 2016 – the UK’s £3bn attempt to keep up with US
3/10 The world's biggest aircraft carriers
A grainy image uploaded via Google as an open source picture, and circulated throughout blogs across the world, this is thought to be part of a huge new class of Chinese carrier
4/10 The world's biggest aircraft carriers
An artist's drawing of the USS Gerald R. Ford, to replace the Nimitz in around 2016. With a displacement of 112,000 tons, it will be the biggest warship in the world
5/10 The world's biggest aircraft carriers
The Japanese competition for naval domination, the former Varyag aircraft carrier, renamed the Liaoning by the Chinese navy once they bought it, will be used as a training vessel for a new class
6/10 The world's biggest aircraft carriers
One of Europe's largest aircraft carriers, but at 858ft and 42,000 tons displacement, it is still much smaller than anything the US can offer. Notably a similar length (if a lot heavier) to the new Izumo
7/10 The world's biggest aircraft carriers
The Arleigh Burke class destroyer - the US's current type for its size. With a length of 505ft (154m) it is significantly smaller than the Izumo
8/10 The world's biggest aircraft carriers
The 10 Nimitz class aircraft carriers are the largest in the world. At around 1,092ft (332,8m) and a displacement of 110,000 tons, they are the current kings of the ocean.
9/10 The world's biggest aircraft carriers
A size comparison between the USS George Washington, a Nimitz class aircraft carrier, and the current largest Japanese offering, the Hyuga class, on the right
10/10 The world's biggest aircraft carriers
The Zumwalt class is the future of destroyers, as envisioned by the US Navy. It will include a hybrid energy system with an electric engine that could one day be used for futuristic laser weaponry. It will combine the functions of a surface battleship and a naval-combat submarine.
"Shipbuilding has been at the centre of many communities across Scotland for hundreds of years, and today we pay tribute to the workers on the Clyde and at Rosyth who have made this project a reality.
"As part of the United Kingdom, I'm confident that shipbuilding in Scotland will have a positive future and continue to thrive."
HMS Queen Elizabeth is now structurally complete and ready to be floated out of her dock for the first time this month, shortly after being named by the Queen.
The two ships are both termed Queen Elizabeth Class aircraft carriers and are being built by the Aircraft Carrier Alliance (ACA), a partnership of BAE Systems, Babcock, Thales and the Ministry of Defence. Overall, six shipyards around the UK - Appledore, Birkenhead, Govan, Portsmouth, Rosyth and Tyne - have been involved in building various parts of the carriers.
There has only been one previous HMS Queen Elizabeth, which was completed 100 years earlier. The new ship's name is both the continuation of this historic Royal Navy name and a tribute to the Queen.
Those behind the project, which costs an estimated £6.2 billion overall, say the QE Class will be the centrepiece of Britain's naval capability.
Each 65,000-tonne aircraft carrier will provide the armed forces with a four-acre military operating base, which can be deployed worldwide, operating the F-35 Lightning II and a number of types of helicopter. They will be versatile enough to be used across the full spectrum of military activity, from war fighting to providing humanitarian aid and disaster relief.
The length of each ship is the equivalent of 28 London buses - almost three times the length of Buckingham Palace.
Each ship, which has a life expectancy of around 50 years, will be fitted out with more than three million metres of cable and it will have enough power to light up a small town.
HMS Queen Elizabeth will have 679 permanent crew and capacity for 1,600 crew members when fully operational.
The Queen and Prince Philip will also visit the Forth Road Bridge to mark its 50th anniversary today.
They will meet a group of long serving employees before unveiling a plaque.