After 620 days in Downing Street, will Rishi Sunak now be California Dreamin'? How PM is leaving No10 with series of unfulfilled pledges - with claims he could now move to his £5.5m Santa Monica penthouse

More than 18 months ago, Rishi Sunak entered No10 saying he was 'not daunted' by the challenge that awaited him as he became Britain's 57th prime minister.

But, 620 days later, the first British Asian premier is leaving Downing Street with a series of unkept pledges after his gamble on a summer general election backfired.

There is now speculation that Mr Sunak could soon leave politics behind and relocate to America - taking with him a £651million fortune that made him the richest ever PM.

He and his wife Akshata Murty, heiress to a billionaire Indian IT mogul, own a penthouse flat in Santa Monica, which is estimated to be worth £5.5million.

Mr Sunak has previously described California as 'very special', as it is where he and Akshata, both 44, first met while they were both studying at Stanford University.

As the youngest ever prime minister to leave office in modern political history, it has been suggested Mr Sunak could return to a career in finance across the Atlantic.

Mr Sunak faced repeated jibes during the campaign that he planned to move to California soon after his forecast defeat, but speaking at the G20 summit in June he insisted he would stay on as an MP for the full five years of a new parliament. 

He later doubled down in an appearance on ITV, where the interview challenged him on a claim by Lord Goldsmith that he would 'disappear in a few weeks'. 

The then PM repeatedly rejected the idea saying: 'It's simply not true, I mean, it's just simply not true.'

When asked if he was committed to staying in Britain, Mr Sunak said: 'Of course, of course I am. Of course, and this is my home.

'I mean, my football team just got promoted back in the Premiership and I hope to be watching them for years to come in the Premier League.'

Despite the shattering overall result, Mr Sunak won his Richmond and Northallerton seat with 23,059 votes -  double Labour's tally - and has vowed to continue representing the area in Parliament. 

His constituency home is a Grade II-listed Georgian Manor house, which he and Ms Murty bought in 2015 and features a swimming pool, hot tub, yoga studio, gym and tennis court in 12 acres of grounds. 

The couple also own a £7m London mews house and a flat on the Old Brompton Road. 

But Ms Murty's shareholding in Infosys, the Bangalore-based IT company co-founded by her father, is by far her and Mr Sunak's most valuable asset.

Their joint wealth is estimated at £651million, with glimpses of their affluence having often been spotted during their time in No10.

The father-of-two has previously made headlines with a £3,500 bespoke suit, a £450 pair of Prada loafers, a £750 luxury backpack, and a £180 'smart' coffee mug.

His personal wealth was the subject of fierce attacks by political opponents when he became PM in October 2022, as Britain was gripped by a cost-of-living crisis.

The financial affairs of his family had even threatened to derail Mr Sunak's political career months earlier, when it was revealed Ms Murty enjoyed non-dom tax status.

Labour accused Mr Sunak, who was then Chancellor, of 'breathtaking hypocrisy' as the row came at a time when the Treasury was hiking National Insurance for workers.

The non-dom row was the first real setback for Mr Sunak during what had been a meteoric rise since he entered Parliament as MP for Richmond, Yorkshire, in 2015.

His time on the Conservative back benches was short as he was appointed local government minister by Theresa May in 2018.

In July 2019, after he backed Boris Johnson as Mrs May's replacement as PM, Mr Sunak was then promoted to Chief Secretary to the Treasury.

Less than seven months later, Mr Sunak was called upon to take over the top job in the Treasury following Sajid Javid's dramatic resignation as Chancellor.

It was less than a month after entering 11 Downing Street that Mr Sunak was unveiling his first Budget, amid the backdrop of the growing Covid crisis.

He was later forced to make a series of interventions in a bid to prop up Britain's economy as the pandemic forced a global shutdown. 

Mr Sunak oversaw the furlough scheme as part of a swathe of business support packages, and - when restrictions were later lifted - he promoted his 'Eat Out to Help Out' initiative.

It was his appearances at Covid press conferences - as well as sleek social media campaigns and largesse with taxpayers' cash - that pushed Mr Sunak into the wider public's attention for the first time.

And his new-found recognition as the man who steered Britain through an economic maelstrom soon saw him touted as a future PM.

But the shine came off 'Brand Rishi' when, firstly, the row broke out over his wife's tax status.

Ms Murty was revealed to have legally avoided paying a huge UK tax bill by paying £30,000 a year to register as based in India.

Mr Sunak insisted his wife hasn't 'done anything wrong' while accusing his critics of 'smearing her to get at him'. She later agreed to pay full UK tax.

Later it emerged Mr Sunak had held a US Green Card for a year into his term leading the Treasury.

While the status would not save him any money on his tax bill, it carries a responsibility to make the US 'your permanent home'.

Another setback hit Mr Sunak when he received a £50 fine for attending Boris Johnson's surprise - and Covid rule-breaking - birthday party in No10 in June 2020.

His supporters blamed No10 for embroiling him in the Partygate controversy, further deteriorating the two men's relationship within Downing Street.

The tensions came to a head on 5 July 2022, when Mr Sunak quit as Chancellor almost simultaneously with Mr Javid's resignation as health secretary.

This was widely seen as the final nail in the coffin for Mr Johnson's premiership - an act for which Mr Sunak has never been forgiven by Mr Johnson's closest allies. 

In his resignation letter, Mr Sunak cited 'fundamental' differences in the two men's economic approach.

He also swiped that the public expected Government to be conducted 'properly, competently and seriously' amid the Chris Pincher scandal.

When Mr Johnson announced his resignation as PM two days later, Mr Sunak swiftly launched his 'Ready For Rishi' campaign to replace him.

The professional nature of his campaign launch raised questions over the length of time Mr Sunak has been preparing a leadership bid.

He sailed through the parliamentary rounds of the Tory contest and emerged as the best-supported candidate among Conservative MPs.

But Mr Sunak failed to win over the party's membership and was defeated by Liz Truss in a ballot of the Tory grassroots.

It followed a bitter summer-long battle between the two rivals, during which Mr Sunak blasted Ms Truss as 'morally wrong' for pursuing a tax-cutting spree at a time of tight public finances.

Yet, despite his loss to Ms Truss, Mr Sunak was to get a second chance at becoming PM when her premiership spectacularly blew up after just 44 days amid economic turmoil.

In the second Tory contest of 2022, Mr Sunak saw off Mr Johnson's attempt at a shock comeback, as well as a leadership bid by Penny Mordaunt, to emerge victorious.

Despite being publicly backed by more than half of Tory MPs for the leadership, Mr Sunak faced an immediate battle to put his disunited party back together following a a rancorous few months.

But the scandals that dogged previous Conservative leaders continued to afflict his premiership, with Gavin Williamson resigning as a minister just a fortnight into Mr Sunak's premiership over bullying allegations.

Further scandals were to follow over Nadhim Zahawi's tax affairs and Dominic Raab's behaviour towards officials. 

Mr Sunak himself suffered personal embarrassment when he was fined by police after a social media video revealed him in a moving vehicle while not wearing a seatbelt.

In January last year, Mr Sunak attempted to define his premiership by setting out five pledges on the economy, the NHS, and halting the Channel migrant crisis.

Although he made progress on the economy with inflation more than halving during his time in No10, Mr Sunak failed to cut NHS waiting lists or 'stop the boats'.

He also appeared to grow increasingly frustrated at his failure to eat into Labour's large lead in opinion polls.

At the Conservative Party conference in Manchester last year, Mr Sunak changed approach and moved away from his oft-repeated five pledges in favour of a policy blitz.

He announced plans to create a smoke-free generation with a phased-in ban on the sale of cigarettes, as well as setting out plans to scrap A-levels and replace them with an English version of the international baccalaureate.

Mr Sunak also confirmed he was scrapping the northern leg of HS2 rail to Manchester in his keynote address to party members in the city. 

Shortly after the Tory conference, there appeared to be a further switch in his strategy as he sacked Suella Braverman as home secretary and - sensationally - returned ex-PM David Cameron to government as foreign secretary.

But he was soon jolted by a bombshell Supreme Court ruling that left his Rwanda migrant deportation plan in disarray as senior judges ruled the scheme unlawful.

This precipitated a long and bitter battle in Parliament - as well as within Conservative ranks - over his attempts to introduce new laws to get around the ruling by senior judges.

As an arduous slog to get flights to Rwanda off the ground continued, Mr Sunak shocked Westminster on 22 May when he used a rain-sodden Downing Street address to call the general election for 4 July - much earlier than most had been expecting. 

Yet his campaign soon plunged into crisis over public outcry at his decision to skip a major D-Day event in Normandy, before he was later struck by a betting scandal.

It meant Mr Sunak moved away from promoting the Tories' manifesto pledges - including the return of a form of national service for teenagers - towards warning about the impact of a Labour 'supermajority' under Sir Keir Starmer.

When election night came, Mr Sunak saw his party suffer an unprecedented routing as they suffered their worst ever election result in the face of a Labour landslide.

In a speech outside No10, Mr Sunak said he would meet the King to offer his resignation as PM but promised to stay on as Tory leader until arrangements could be made to choose his successor.

'To the country, I would like to say first and foremost, I am sorry,' he said before he departed Downing Street for the final time.

'I have given this job my all, but you have sent a clear signal that the Government of the United Kingdom must change. And yours is the only judgment that matters.

'I have heard your anger, your disappointment, and I take responsibility for this loss.'