Boris Johnson wants to replace a series of mandarins as part of a move to change dramatically the approach in some of Whitehall’s most influential departments, Tory sources claim.

Senior Tories said No 10 sees Sir Tom Scholar, the Treasury permanent secretary, who previously led David Cameron’s attempted renegotiations with the EU, as “offside” on Brexit and his approach to the economy.

Sir Tom is said to top a “s---list” of permanent secretaries No 10 wants replaced over claims that they are significantly at odds with Tory ministers and advisers, who have been buoyed by Mr Johnson’s landslide election win.

The disclosure comes after a major row between Priti Patel and Sir Philip Rutnam, the Home Office permanent secretary, boiled over last week with the disclosure that the Home Secretary had attempted to remove her top official after a series of clashes.

Sir Philip was accused of “obstructing” and “undermining” successive home secretaries.

Tory sources said Sir Tom, 51, and Sir Philip, 54, were among three permanent secretaries Downing Street wanted to replace, along with Sir Simon McDonald, 58, the most senior civil servant at the Foreign Office, who worked alongside Mr Johnson when he was foreign secretary.

In a separate clash, Baroness Morgan of Cotes, the former culture secretary, today warns the BBC that reform of the corporation is “unavoidable”, adding: “The best way to tackle it is to start the ball rolling yourself.”

Writing in The Sunday Telegraph, Lady Morgan, who stepped down from government earlier this month, states that the next BBC director general would “best aid their cause by accepting that ‘no change’ is not an option”.

It follows a highly personal attack by David Dimbleby, the broadcaster, over what he described as Mr Johnson’s “pernicious” attempt to decriminalise non-payment of the BBC licence fee.

Asked about Downing Street’s concerns about Sir Tom, a senior Tory source said: “Scholar is offside completely on Brexit. The Treasury has done nothing but dig their heels in.

“Their view on the economy is now very different to the view in Downing Street ... I can’t see how he’s going to carry on.”

A second Tory source added: “There are a few permanent secretaries that are on the ‘s---list’ who, given we’ve now got five years and a majority, won’t be there very long.”