Penny Mordaunt MP

The prime minister is considering the proposal, devised by Penny Mordaunt during her stint as international development secretary.

The PM held private talks with the Portsmouth North MP over the summer – weeks after he sacked her from his cabinet.

Now it’s understood Mr Johnson could bring forward the proposals ahead of a formal written submission.

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Royal Yacht Britannia as she visits Portsmouth. Photo: PA Wire

The development excited Ms Mordaunt, who said Portsmouth could reap the rewards.

‘There is huge interest and I hope, if we can get this off the ground, that Portsmouth’s supply chain would benefit and potentially we could be their base port,’ she told The News.

The new vessels, with one called ‘Britannia’ and the other named the ‘Florence Nightingale’ or ‘Mary Seacole’, would be used by members of the Royal family for overseas tours to the Commonwealth and other countries.

The first ship would cost around £150m, with the second slightly less.

The original HMY Britannia was a regular sight in Portsmouth. It is now a tourist attraction in Edinburgh after it was controversially decommissioned by Tony Blair, the former prime minister, in 1997.

Mr Johnson told party members during the Tory leadership campaign that he would ask the Queen if she wanted a new yacht before commissioning one in July.

Speaking to the Daily Telegraph, Ms Mordaunt added: ‘Growing up in Portsmouth, I know why people loved Britannia so much.

‘She was a striking symbol of our nation's history and our intent on the world stage.

‘She is still incredibly popular. I think that we can harness that heritage in some new modern vessels with a [more] practical focus on doing the things we want to do around the world.’

The former defence secretary added she has already been in talks with the Royal Navy over the vessels – which could be used by the Senior Service during times of conflict.