This is HMS Illustrious as you have probably never seen her before – from below.

And you won’t see her like this again for some time to come, either.

In a 270m-long dry dock at Rosyth dockyard in Scotland, the 26-year-old carrier awaits the moment the sluice gates are opened and she is afloat once more as the latest stage of her refit is completed.

‘Lusty’ is the last of the Royal Navy’s three Invincible-class aircraft carriers to be converted to operate the Merlin helicopter.

That conversion – as well as other upgrades and overhauls for the veteran of the Afghanistan campaign – has reached the half-way stage.

Before opening the sluices to flood up the dock, staff from Babcock Engineering, who are carrying out the work on Illustrious, celebrated with a tea party on the dock floor alongside crew.

Guests enjoyed tea under the carrier’s bow, then walked right under the ship – she has a flat bottom, which surprised many people – to the stern for some short speeches to celebrate the progress on the ship.

“A warship which displaces 20,000 tonnes, sits 210 metres long and measures 36 metres across is a spectacular and unforgettable sight out of the water,” said Archie Bethel, Babcock’s Managing Director.

Cdr Mike Martin, the Commanding Officer of Illustrious during her refit stage, added: “This is a very significant moment for Lusty as there are certain functions which can only be commissioned when she is in her natural habitat – at sea.

“The closer she gets to sea readiness, the more the Royal Navy and the crew of Illustrious play a hands-on role.”

This has been the first refit for Illustrious in ten years and will help her continue service into the next decade – until the first of the next generation of carriers, expected to be well over twice the size of the Invincible-class ships, enters service.

Illustrious should be ready for trials at sea in the late summer.