The ex-chief secretary was promoted from the number two job at the Treasury after his former boss quit in the bloody outcome of a power struggle with Number 10 aide Dominic Cummings.
Mr Sunak arrives just 27 days before he will have to deliver his first Budget on 11 March, and attention will now be focused on what changes he will make to the taxation and spending plans drawn up by Mr Javid.
Reports suggests that he accepted Mr Johnson’s demand – rejected by Javid – for his special advisers to form part of a joint unit for 10 and 11 Downing Street appointed directly by Number 10.
The move effectively puts the relatively inexperienced Sunak’s advisers directly under Number 10’s control, in what was being seen as a power grab by Cummings which could leave him as “chancellor in name only” (Chino).
His surprise appointment at 39 and after less than five years in parliament makes him the second youngest Chancellor in more than a century, behind George Osborne.
But he wields far less personal clout than Osborne, who made up part of an effective power duo with close ally David Cameron when he entered 11 Downing Street aged 38 in 2010.
Javid’s insistence on sticking to his fiscal rules of balancing the current account budget by the middle of the next parliament and limiting borrowing for infrastructure to 3% of GDP is believed to have been the cause of tensions with 10 Downing Street, where Boris Johnson was eager to pour money into major building projects to stimulate the economy.
Sunak arrived in the House of Commons only in 2015 as MP for Richmond in Yorkshire and was appointed a junior environment minister by Theresa May in 2018.
He joined fellow up-and-coming “one nation” Tories Robert Jenrick and Oliver Dowden in making a high-profile declaration for support for Johnson in last year’s leadership battle and was rewarded last July with the post of chief secretary, attending cabinet.
The son of a GP and pharmacist from Southampton, in 2009 Sunak married Akshata, the daughter of Indian billionaire Narayana Murthy, the co-founder of Infosys. The pair met while studying at Stanford University in California.
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