Boris Johnson’s new chief of staff once described himself as the “mug” who took on the job of putting together a budget for the 2012 London Olympics while working as a senior Treasury official.

Dan Rosenfield is now responsible for restoring order to Downing Street after weeks of chaos which saw two of the Prime Minister’s closest aides leave Number 10 in a swirl of controversy.

But Mr Rosenfield is no stranger to turbulent times at the centre of power having worked closely with then Labour chancellor Alistair Darling during the financial crisis of 2008 and also with Tory successor George Osborne as he ushered in the age of austerity two years later.

Starting his career as a Treasury policy adviser in 2000, Mr Rosenfield swiftly rose through the ranks as five years later he took a pivotal role at the heart of Britain’s burgeoning Olympic ambitions.

“I was the mug who took the job on of leading the Treasury effort at putting a budget together for the Olympics the day after we won the bid.

“There were not many people in the Treasury who were expecting us to win the bid.

“There was no meaningful budget or plan, so we were starting from not far off the bottom,” he told the Jewish Telegraph.

Mr Rosenfield then moved on to the role of principal private secretary to chancellors Mr Darling and Mr Osborne during some of the most tumultuous years the Treasury has experienced in recent decades before the coronavirus crisis.

Dominic Cummings (Aaron Chown/PA)

He said: “I was dealing with a job involving a lot of pressure, such as getting a call at 9am on a Saturday with instructions from the Prime Minister to do X, Y and Z by Monday morning.”

Mr Rosenfield left for the private sector, becoming managing director at Bank of America and ending up in a senior role at strategic advisory firm Hakluyt, and also becoming chairman of humanitarian agency World Jewish Relief.

Mr Rosenfield’s arrival follows the abrupt departure of Mr Johnson’s highly controversial chief adviser Dominic Cummings, and the Downing Street head of communications Lee Cain, amid incendiary in-fighting at the heart of power.

The pair left after an explosive row over a proposal to appoint Mr Cain to the key Downing Street post of chief of staff, a move reported to have been been opposed by Mr Johnson’s fiancee Carrie Symonds.

The Olympics turned out to be a national triumph but, as one of the few people with direct access to the the Prime Minister, Mr Rosenfield may have his work cut out once again trying to bring Downing Street together.