Before his spectacular falling-out with Boris Johnson, former finance minister Rishi Sunak was on a rapid rise that could still end with him installed as Britain's first prime minister of colour.

It would be a historic landmark, if the Hindu descendant of immigrants from Britain's old empire in India and East Africa were to take command of the world's fifth largest economy.

But after making the final run-off following a series of votes by Conservative MPs, Sunak must first convince the party's grassroots members -- and hope Johnson loyalists overlook his role in toppling the scandal-tainted leader.

A details-oriented policy wonk, Sunak, 42, was an early backer of Brexit, and took over as chancellor of the exchequer in February 2020.

It was a baptism of fire for the Tory rising star, as the Covid pandemic erupted.

Rishi Sunak is a rising star among Conservatives and could be Britain's first Hindu PM
Rishi Sunak is a rising star among Conservatives and could be Britain's first Hindu PM AFP / DANIEL LEAL-OLIVAS

He was forced to craft an enormous economic support package at breakneck speed, which he now says needs to be paid off.

In India, Sunak has been better known through his wife Akshata Murty. She is the daughter of Indian tycoon Narayana Murthy, the billionaire co-founder of information-technology group Infosys.

The Sunaks met while studying in California and they have two young daughters -- along with a photogenic dog.

The ex-minister's Instagram-friendly profile earned him the media nickname of "Dishy Rishi".

But Sunak, already wealthy through his pre-politics career in hedge funds, must battle against criticism that he is out of touch with ordinary Britons struggling with a cost-of-living crisis.

This week, video footage emerged of a 21-year-old Sunak describing his mix of friends following his education at Winchester College, one of Britain's most exclusive private schools, and Oxford University.

Rishi Sunak on Wednesday made the final run-off to decide Britain's next Conservative leader and prime minister
Rishi Sunak on Wednesday made the final run-off to decide Britain's next Conservative leader and prime minister AFP / Niklas HALLE'N

"I have friends who are aristocrats, I have friends who are upper class, I have friends who are, you know, working class," he said, before adding: "Well, not working class."

Until last year, Sunak held a US Green Card -- which critics said suggested a lack of long-term loyalty to Britain.

And he is bound to face fresh questions over Murty's failure until recently to pay UK taxes on her Infosys returns, which opinion polls suggest was viewed with deep disfavour by voters.

Sunak is married to Akshata Murty, whose father co-founded the Indian tech giant Infosys
Sunak is married to Akshata Murty, whose father co-founded the Indian tech giant Infosys POOL via AFP / Tristan Fewings

Sunak has already been marked by the scandals of Johnson's tumultuous premiership.

In 2020, he marked the Hindu festival of Diwali by lighting oil lamps on the front step of the chancellor's official residence at 11 Downing Street -- while urging other Hindus to stick to England's Covid lockdown.

That same evening of November 13, 2020, Johnson and his partner Carrie were allegedly violating the lockdown by partying with friends to celebrate the downfall of his then-chief advisor, Dominic Cummings.

The apparent rule-breaking and history of mendacity attached to the "Partygate" premier are in contrast to the teetotal Sunak, who admits only to a fondness for Coca-Cola and sugary confectioneries.

But he still ended up with a police fine for Partygate, after joining a birthday gathering for Johnson when he arrived early for a Downing Street meeting.

Sunak was barely known to the British public when Johnson made him chancellor, after only five years in Conservative politics.

He was the first person born in the 1980s to hold one of the so-called four great offices of state: prime minister, chancellor, foreign secretary and home secretary.

He represents the constituency of Richmond in Yorkshire, northern England -- a safe Conservative seat he took over in 2015 from former party leader and foreign secretary William Hague, who described Sunak as "exceptional".

Sunak swears his oath of allegiance as an MP on the Bhagavad Gita. Theresa May gave him his first job in government in January 2018, making him a junior minister for local government, parks and troubled families.

Sunak's grandparents were from Punjab in northern India and emigrated to Britain from eastern Africa in the 1960s.

They arrived with "very little", Sunak told MPs in his maiden speech in 2015.

His father was a family doctor in Southampton on the southern English coast, and his mother ran a local pharmacy.

Sunak waited tables in a local Indian restaurant, before progressing to Oxford and then Stanford University in California.

Both his own family's experience, and that of his wife's, are a "very Conservative" story of hard work and aspiration, Sunak said at a bad-tempered candidates' debate last week.

The coming weeks will decide if that resonates enough with most of the Tory rank and file.