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.
Ten thousand workers at six different shipyards have been involved in her construction, including hundreds from Southampton who travelled to Portsmouth everyday for work after losing their jobs at Vosper Thornycroft.
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.
''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.
The man overseeing the construction of the ship, Queen Elizabeth Class programme director Ian Booth of the Aircraft Carrier Alliance, told BBC Radio 4's Today: ''We now have very flexible warships which have been designed to meet the UK's military maritime needs for the next 50 years. They are really flexible ships with massive capability built into them.
''They are effectively a floating military city that can deploy aircraft, that can act as a disaster relief centre. They have their own hospital with operating theatres. They can support land forces, all sorts of military interventions.
''There are many challenges in the programme. The first major challenge was to build the physical ship. We used six shipyards around the UK, ranging from Glasgow to Appledore, Portsmouth, the Mersey, the Tyne, and then finally we've integrated the ships here in Rosyth, in Scotland. So the major challenge was getting all those units made on schedule, and I'm proud to say that all of those items were shipped to Rosyth on time.
''The companies are all united around the common goal of delivering two warships to the Royal Navy of high capability and high flexibility. There's a real spirit amongst the team of galvanising around that goal, and it's an immensely proud moment for all of us that we've brought this first ship together in Rosyth.''
Mr Booth said the ship is so big that a ''plat-nav'' GPS system had been developed to help workers find their way round its 3,000 compartments.
''I'm very proud today,'' he said. ''This is the culmination of a great amount of work to build this magnificent warship. Ten thousand people have worked on it across the UK, 1,000 youngsters have begun their careers on this programme.
''We are really feeling immensely proud to name the ship today and to have the Queen here to do that.''