She will remain at Rosyth until Saturday (July 5).

“This is a milestone moment in the history of the Royal Navy,” said HMS Illustrious’ Commanding Officer, Captain Mike Utley.

“And we are proud to play our part in the occasion.

“It is the only time that HMS Queen Elizabeth and HMS Illustrious – as carrier capability present and future – will sit side-by-side, making this a unique moment.”

HMS Illustrious is the UK’s high readiness helicopter and commando carrier. This means that she can fulfill a variety of tasks anywhere around the world.

Duties could include the use of helicopters such as Merlin, Sea King, Lynx or Apache and embarking Royal Marines Commandos. Illustrious and her ship’s company are fully prepared to respond to global operations at extremely short notice.

HMS Illustrious was one of two Royal Navy ships – the other being HMS Daring – which responded to the humanitarian disaster in the Philippines in the wake of Typhoon Haiyan in November last year.

The ship is protected by three Goalkeeper anti-aircraft and anti-missile weapon system, with advanced radar systems that quickly detect incoming fire, determine the trajectory, aims and fires - with no human input.

These, of course, would provide her first line of defence against any surface threat. Depending on the operational mission, Illustrious may also have as an escort one of the Royal Navy’s anti-submarine frigates or state of the art Type 45 destroyers, completing her robust defensive line-up.

HMS Illustrious is the second of three Invincible-class light aircraft carriers built for the Royal Navy in the late 1970s and early 1980s. She is the fifth warship and second aircraft carrier to bear the name Illustrious.