Boris Johnson has appointed an ex-Treasury official as his new chief of staff, Downing Street has announced.
Dan Rosenfield's appointment follows a period of upheaval which saw the prime minister's senior aides Dominic Cummings and Lee Cain resign.
Mr Rosenfield is former civil servant, who has worked in the past for Labour chancellor Alistair Darling and his Tory successor George Osborne.
He will begin work at Downing Street on 7 December.
The current acting chief of staff Lord Udny-Lister will stay in the role until 1 January when Mr Rosenfield will take over.
Cleo Watson, one of the PM's deputy chiefs of staff, who was close to Mr Cummings, is also leaving No 10.
Mr Rosenfield joins No 10 from Hakluyt, a strategic advisory firm.
He has also previously worked at Bank of America as a managing director and is chairman of the humanitarian agency World Jewish Relief.
The chief of staff role had originally been offered to Mr Cain, however some MPs and ministers objected to the appointment.
And following a power struggle inside No 10 both Mr Cain and his ally Mr Cummings stepped down from their roles.
This senior job hasn't gone to a high-profile name from Tory ranks as some expected, but a former civil servant.
While he has worked at the heart of government in his role at the Treasury, he is a relative outsider in current political circles.
Those who know Dan Rosenfield describe him as likeable, clever and effective.
One former Treasury colleague said he was ordered and efficient.
"If the wheels are coming off he'll want to try to put them back on", they added.
Having been in the private sector in recent years, he's not thought to be attached to any particular faction in No 10; perhaps that was part of the thinking behind his appointment.
After the recent turbulence that saw the departure of two of Boris Johnson's closest aides, Downing Street will want to avoid any further internal division.
Many have called for a "reset moment".
The prime minister may well hope this pick for chief of staff is part of that.
Mr Rosenfield grew up in what he describes as a "small Jewish community" in Manchester.
In an interview last year with the Jewish Telegraph, Mr Rosenfield describes Judaism as being "pretty central" to his life and says his local synagogue was his "second home".
He also recalls working in the Treasury during the 2008 financial crisis. "It became very clear that we were dealing with some quite fundamentally difficult challenges," he said.
Speaking at a World Jewish Relief dinner in 2017 he said he was driven by the principle of "the rejection of tragedy in the name of hope".
Welcoming the appointment, ex-Treasury Minister David Gauke described Mr Rosenfield as "smart, likeable and effective".
And a former Labour adviser Damian McBride said the PM's new recruit had "a first-class brain and an easy smile".
His previous employers Hakluyt are a low-profile consultancy firm with offices in Mayfair, central London, as well as New York, Mumbai, Singapore, and Tokyo.
The company says it is named after the English writer Richard Hakluyt "because his role in advancing knowledge of the wider world in the 16th and 17th centuries... reflects the firm's global interests and independence of thought".
It is chaired by the Conservative peer Lord Deighton - who was recently given a role co-ordinating the drive to scale up UK manufacturing of personal protective equipment (PPE).