A successor to the Royal Yacht Britannia could drum up trade among Commonwealth nations as President Trump’s tariffs shake the world economy, according to a leading champion of a new vessel. Businessman Ian Maiden, 91, has invested hundreds of thousands of pounds in plans for a “national flagship” and has lobbied the King and the Prime Minister as he builds support.

He argues a flagship could be put to work championing trade long before other pro-growth projects – such as a new runway at Heathrow – become reality.

Mr Maiden and his team developed a design after then-Prime Minister Boris Johnson announced plans for a new vessel in 2021, but the competition to build the flagship was dropped the next year.

In his letter to the King, Mr Maiden described the process as “long, arduous and horrifyingly expensive” – but he has not lost faith in the project’s potential.

He is willing to offer the design free for use by the Commonwealth, and he is optimistic private sources of finance could fund the £250million construction cost.

Champions of a new vessel argue that Britannia helped bring in billions of pounds of trade deals in the 1990s – and Mr Maiden is convinced a new ship would wom international attention.

He said: “This is one means which is a proven way of getting extra business... It’s a great way of meeting the Government’s requirements for expanding the economy.”

Mr Maiden – who made his fortune in outdoor advertising – thinks it could be constructed within a maximum of three years, and he is excited at the thought of the Prince and Princess of Wales using it to champion trade overseas. If William and Kate arrived in Mumbai on such a ship, he said, “the press coverage would be worldwide”.

He hopes it would be built in a British shipyard and suggests it could double as a disaster relief vessel.

“This fresh initiative might be the very catalyst to raise the voice of the Commonwealth on the world stage,” he states in his letter to the King.

According to the Commonwealth, the family of nations is home to 2.7 billion people, six out of 10 are aged 29 or under. The organisation states on its website its combined GDP is estimated to reach $19.5 trillion in 2027.

In a letter to the Sir Keir Starmer, Mr Maiden says he expects the Commonwealth’s combined GDP to overtake that of the EU.

He states: “Our vessel’s design work is oven-ready to pass to a shipyard of choice... Few things are absolutely certain but it does seem that all the capital cost will fall to the private sector.

“This growth initiative might sit comfortably alongside the much longer term growth plans including the expansion of Heathrow Airport.”

Although the new project will trigger comparisons with Britannia, Mr Maiden does not describe it as a new “yacht”.

He said: “I don’t use the world ‘yacht’ because people think of pleasure cruises but a ship is a very effective way [of generating trade].”

Britannia entered service in 1954 and sailed more than one million nautical miles but was decommissioned after making its final visit to Hong Kong in 1997. The vessel is now a tourist attraction in Edinburgh where the clocks remain stopped at 3.01pm – the time Queen Elizabeth II was piped ashore for the last time during the decommissioning ceremony.