Both the Palace and the MoD declined to comment on his involvement.

Discussions about renaming the submarine – which is being built in Barrow, Cumbria – started more than a year ago – while Shapps was still in office.

One defence source suggested the King had initiated those discussions.

The names of ships and submarines are put forward by the Royal Navy’s Ships’ Names and Badging Committee and then approved by the monarch.

HMS Agincourt was the name agreed under Queen Elizabeth II, but defence sources say King Charles wanted another name and has given his approval to HMS Achilles instead.

The Royal Navy said “the name was proposed by the Royal Navy Ships’ Names and Badging Committee and approved by his Majesty the King”.

The Navy said HMS Achilles was particularly appropriate as this year marked the 80th anniversary of the end of World War Two, in which an earlier HMS Achilles received battle honours.

The original name, HMS Agincourt, was first announced in 2018, by Sir Gavin.

It would have been the sixth Royal Navy vessel to bear the name of the famous victory in 1415, when Henry V’s Army defeated the French.

But there were concerns – both within and outside the Ministry of Defence – that reviving the name could cause unnecessary offence to France – a key ally.

Sir Gavin branded name change a “woke moment” in what he called the “pathetic” Ministry of Defence, while Shapps decried the decision as “sacrilege” and evidence of “Labour’s woke nonsense”.

Chris Parry, a former Nato commander, also told Times Radio that the decision to rename the submarine was “craven political correctness and ideology gone mad”.