Five years ago Britain's new finance minister Rishi Sunak was not even a member of parliament, now he is running the world's fifth largest economy. 

The 39-year old former Goldman Sachs banker was appointed in dramatic fashion today when incumbent Sajid Javid unexpectedly quit during what Downing Street had cast as a routine ministerial reshuffle. 

As Johnson moves to increase control of the finance ministry, one of the youngest chancellors in history will face a prime minister who wants to increase spending on everything from infrastructure and police to health and education. 

"Delighted to be appointed," Sunak said. "Lots to get on with." 

Sunak, seen as a rising star in the ruling Conservative Party since he entered parliament in 2015, had been tipped for promotion to a senior post in the ministerial rejig as Johnson put together his post-Brexit cabinet. 

But, despite an already rapid ascent through the ranks of government, few expected the Oxford University Politics, Philosophy and Economics graduate to ascend to one of the highest offices in the land. 

Sunak had been serving as Javid's deputy in the finance ministry since Johnson promoted him upon taking office in July 2019. Prior to that he had served as a junior housing minister. 

"From working in my mum's tiny chemist shop to my experience building large businesses, I have seen first-hand how politicians should support free enterprise and innovation to ensure our future prosperity," Sunak says on his website. 

Seen as a smooth media performer and ultra-loyal member of the Conservative Party, Sunak has been used by the government to present and defend their policies in television interviews - a sign of trust from Johnson, who has a fraught relationship with Britain's media. 

Sunak takes control at a critical juncture for Britain's $2.7 trillion economy. 

He will have to steer the economy through the turbulence of leaving the European Union and the forging of new trade links that will define Britain's new relationship with the world. 

However, the power struggle that forced his predecessor Javid to quit hints at a more diminished role for what is the second most powerful position in government - with Johnson's office wanting to centralise control and minimise dissent. 

Sunak is married to the daughter of an Indian billionaire, co-founder of IT services company Infosys Narayana Murthy, and was hand-picked to take over an ultra-safe seat in northern England, previously represented by former Conservative Party leader William Hague. 

Hague has described Sunak as an "exceptional individual". 

Sunak's father was a doctor and his mother ran a chemist shop. 

Before entering politics he worked for Goldman Sachs and a hedge fund, then co-founded an investment firm. He also has an MBA from Stanford University in the US.