The new member of Prince William and Kate's inner circle

Prince William has appointed a new private secretary who he will work closely with, Kensington Palace has confirmed.

Jean-Christophe Gray, previously a spokesperson for the former Prime Minister David Cameron, joined the Duke of Cambridge's team last week.

Gray takes over the senior role after previous private secretary Christian Jones left after almost a year to work for private equity group Bridgepoint.

The 45-year-old former political advisor worked closely with leaders of the UK in the government's Treasury Department as head of general expenditure policy.

According to The Sunday Times, Gray was known as "mild-mannered", though an anonymous source likened his strict approach to conserving money to a "velociraptor".

Westminster sources told the publication Gray was "the model of a mandarin high-flyer: clever, a little geeky and beyond reproach".

Gray's frugal mentality appeals to the duke, who was previously said to refuse to spend money on official engagements if he felt they were not a justifiable use of taxpayer funds.

According to accounts published in 2020, the royal family spent £5.3 million ($AUD 9.43 million), up from £4.6 million ($AUD 8.19 million) in 2018-19. 

Kate Middleton also lost her right-hand woman last year when her private secretary called it quits, two years into the royal role.

Catherine Quinn signed on as the Duchess of Cambridge's secretary in October 2017, following the departure of Rebecca Deacon, who had been working with the royal family for more than a decade.

Tasked with planning Kate's daily schedule and accompanying her to official engagements, Quinn was by the duchess' side for two years but left the job to "take a step back".

RELATED: Kate's right-hand woman calls it quits

A source said the mother of one "simply wants to take a step back and focus again on her charity work," according to The Daily Mail.

"She has done an incredible job but just wants some more time for other interests."

Quinn and Kate formed a close friendship while working together and are said to be parting on good terms.

The Cambridges recently celebrated Princess Eugenie announcing the name of her and husband Jack Brooksbank's newborn son to the world.

The new parents, who welcomed their first born child on February 9, shared the name on Instagram with a series of photos, which Kate and Wills 'liked' from their official Instagram account, Kensington Royal.

RELATED: Princess Eugenie and Jack Brooksbank introduce their son to the world

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