If he cherished the moment or savoured the win after losing out in the Tory leadership contest in the summer, Rishi Sunak kept it from view.

From his audience with the King straight to Downing Street, the new prime minister went straight to the lectern and made his inaugural address to the nation.

There were no staffers or MP supporters applauding their man. His wife did not stand outside No 10 and look on.

Sunak’s first full day in the top job – live updates

From the choreography of the moment to the words he spoke, much about Mr Sunak’s launch day was an attempt to show the public his premiership was a break from the past – which is exactly how he wanted it.

Because this is a prime minister who resigned from Boris Johnson’s government after concluding that the business of government was not being conducted “properly, competently or seriously”.

He is a prime minister who warned Liz Truss that her “fantasy economics” would damage the economy. In the end, he had little time for either politician politically or policy-wise, and he used his first speech to try to and put clear blue water between him and them.

When it came to Ms Truss, Mr Sunak was crystal clear – telling the public what she chose not to in her short final speech outside No 10.

“Some mistakes were made,” he told the public as he acknowledged he has been made leader “to fix them”.

And he also took a swipe at the policies – those unfunded tax cuts – she tried to implement as prime minister and which he detested, making it clear that his approach was different to hers: “The government I lead will not leave the next generation, your children and grandchildren, with a debt to settle that we were too weak to pay ourselves.”

When it came to Mr Johnson, Mr Sunak on the one hand praised his “warmth and generosity of spirit” – but on the other, he indirectly criticised the manner in which he ran his administration.

“This government will have integrity, professionalism and accountability at every level. Trust is earned. And I will earn yours,” he said.

Read more:
Sunak prepares for his first PMQs in the top job
Who’s in and who’s out in the new-look cabinet
The key words in Rishi Sunak’s speech

And finally, Mr Sunak made a pledge to the public that he’d turn the page on Conservative Party introspection and infighting and “put your needs above politics”.

“I understand too that I have work to do to restore trust after all that has happened.”

But this was a speech that also hinted at what was to come – with possible spending cuts and tax rises to help tackle the “profound economic crisis” the country is facing.

This a former chancellor-turned-PM who wants to right the wrongs of his predecessor and put “economic stability and confidence at the heart of this government’s agenda”, while sticking very clearly to the promises made in the 2019 manifesto as he sought to claim a mandate for his appointment, rather than public election, on the back of Mr Johnson’s general election win.

There would be “difficult decisions” ahead. His new fiscal plan is expected next week, in which he will have to try to reassure the markets that debt is under control, and outline some of those agonising choices over possible tax rises and spending cuts.

Perhaps that’s why faced with this level of economic pain, Mr Sunak didn’t choose to make significant cabinet changes.

Big beast moves (and more bruised egos) are a risk he was not minded to take right now.

The Change PM became Mr Continuity Cabinet as he kept Jeremy Hunt as chancellor and James Cleverly as foreign secretary.

He even brought Suella Braverman back as home secretary, despite her having to resign from that role just six days ago for a security breach (sending official documents via her personal email) which broke the ministerial code.

Overall, about a third of his cabinet were still in post. He did, however, try to build a unity cabinet in a way that his two predecessors did not – bringing in Ms Braverman and Kemi Badenoch from the right of the party, and keeping Liz Truss’s deputy and key ally Therese Coffey in this top team.

There were jobs too for arch-Johnsonites, be that James Cleverly at the Foreign Office or Chris Heaton at the Northern Ireland office.

He also brought back experience and brought in his own people – be that putting Michael Gove back into the department of levelling up, or his key ally Oliver Dowden into the powerful Duchy of Lancaster role to run the Cabinet Office.

Click to subscribe to the Sky News Daily wherever you get your podcasts

Grant Shapps was put into the Department of Business while Dominic Raab was reappointed deputy prime minister and made justice secretary.

“Unity, experience and competence” is how one No 10 insider explained the reshuffle to me last night. “We do need a bit of experience around the cabinet table with the economy and the international situation.”

He will need all the help he can get from this team in the coming days.

For this is a new prime minister who is about to be tested in the toughest set of political and economic circumstances than any leader has faced in decades.

The lingering question has to be whether he is up to the extreme challenges of being prime minister.

At just 42 years old, he is the youngest serving prime minister in over 200 years and has clocked up just seven years in parliament and three years in cabinet.

He is relatively untested and has, say his critics, displayed a shocking lack of political nous for someone with ambitions for the highest office.

They point to revelations in April that Mr Sunak’s multimillionaire wife Akshata Murty was claiming non-domicile status – a scheme that allows people to avoid tax on foreign earnings – when her husband was chancellor as politically naive (Ms Murty has since changed her tax status).

There was also his admission that he’d held a US green card for two years – which means he had to pay US tax on worldwide income and pledge the US as his forever home – while serving as chancellor, with perhaps ambitions to run as PM.

Whether he was advised badly, or he didn’t see the red flags himself, these were scandals that could have been avoided, which in turn question his judgement.

Read more:
Why is Sunak casting such a sombre mood?
How yesterday unfolded – in pictures
What does the prime minister actually do?

That political judgement was questioned again within hours of him becoming prime minister, as he reappointed Ms Braverman as home secretary.

It was all too easy for the Labour Party, who derided the new prime minister for pledging professionalism while putting – to quote shadow home secretary Yvette Cooper – someone “so careless and slapdash into that job”.

Meanwhile, his decision to leave his challenger Penny Mordaunt in the relatively junior cabinet role of Leader of the Commons – friends told me she wanted foreign secretary – may have been seen by her backers as a rather peevish thing to do, although one of her supporters told me Ms Mordaunt was happy with the job.

But for all the politics of this moment, it is the policies that will matter for Mr Sunak in the coming days as he tries to set out an economic plan that will reassure the markets, his party and the public, that he is up to the job and can handle the task in hand.

He told the British public on the steps of Downing Street that he “understood how difficult this moment is”.

This no doubt a message to himself too.