Outgoing British Prime Minister Boris Johnson has made a surprise visit to meet Australia’s Defence Minister Richard Marles and spruik the AUKUS submarine pact as one of his final acts in power.

Mr Johnson is due to be replaced as PM early next week by either Rishi Sunak or Liz Truss and in a break from tradition the Queen will make the appointment at her Scotland residence, where she spends summer.

Because of her mobility issues, the 96-year-old monarch will meet Mr Johnson and his successor on September 6 (local time) at Balmoral Castle rather than Buckingham Palace.

In one of his last appearances as PM, Mr Johnson travelled unannounced to England’s north where Mr Marles was attending the commissioning of a nuclear submarine HMS Anton.

The Astute class nuclear-powered attack sub will be available to Australian naval officers.

Mr Marles had been due to meet only his British counterpart, Defence Secretary Ben Wallace, and had left London off his itinerary amid the Tory party’s leadership tussle.

Our relationship with the UK is as historic as it is forward-looking.

At Barrow-in-Furness today, I was very pleased to sit down with @BorisJohnson and @BWallaceMP.

We discussed how we can continue to strengthen our #AUKUS partnership collaboration in the Indo-Pacific. pic.twitter.com/F9SaGcM61V

— Richard Marles (@RichardMarlesMP) August 31, 2022

It was announced that for the first time Australian submariners would train inside UK submarines in preparation for the arrival of nuclear-powered vessels as part of the AUKUS security pact.

The Australian navy will train on HMS Anson and four other Astute class submarines alongside UK crews.

“Australia is eager to learn from our counterparts, and who better to learn from than our friends in the United Kingdom,” Mr Marles said at the BAE shipyard in Barrow-in-Furness in northern England.

“Our countries are working hand in glove on training, and building the skills required for our future submarines is an important part of bolstering our defence force.”

The Defence Minister, who is also Deputy Prime Minister, said the opportunity for Australians to train aboard HMS Anson “says everything about our future plans of building the AUKUS partnership”.

The 18-month consultation period under which the Australian government will decide whether to buy US or British-made nuclear-powered submarines is coming up in March 2023.

Mr Johnson called the subs “the policemen of the world” and said they would be used to gather intelligence, protect sea lanes and be guarantors of peace.

“Under the AUKUS agreements with Australia and with the United States, the technology we hope in the submarine will be used to help keep people safe across the whole of the Pacific region as well,” he said.

A fascinating visit today to BAE Systems Academy for Skills and Knowledge here in Barrow with @BorisJohnson and @BWallaceMP.

From training to partnerships, it is an example of what Australia will need as we acquire nuclear-powered submarines under #AUKUS. pic.twitter.com/b48d8nDQyu

— Richard Marles (@RichardMarlesMP) August 31, 2022

“That is the first time we’ve done ever something like this,” Mr Johnson said.

“This is going to represent the UK’s influence and values – the things we love and believe in – around the world, and the thing that is so wonderful seeing our Australian friends here today is that they want to do that with us.

“You’re seeing a partnership developing between the UK and Australia and America, the kind that never existed before – I’m very proud of it. I know the next [British] leader will be wanting to push that as well.”

The British Ministry of Defence said Britain and the US had already welcomed Australian personnel to specialised nuclear training courses, and more will follow next year, before Australian submariners go to sea.

The training and exchanges “mark the beginning of a multigenerational naval partnership between the three AUKUS nations,” British officials said.

-with Reuters and PA