He has forged a reputation as Boris Johnson’s ruthless Downing Street hitman and master strategist.
But the Prime Minister’s chief adviser Dominic Cummings found himself on the receiving end of an unlikely rebuke at Friday’s weekly meeting of ministerial aides.
Former Scottish journalist Lynn Davidson, who works as media adviser to Defence Secretary Ben Wallace, was so unsettled by Cummings' “unkindness” she risked her own future by challenging his behaviour.
Davidson was upset that Cummings had targeted “vulnerable” colleagues during a previous debriefing.
She felt he had picked on fellow aides who knew they could soon be sacked in Thursday’s cabinet reshuffle.
It is claimed Cummings bombarded some advisers with questions he knew they couldn’t answer.
The meeting was held before Johnson announced his new team of ministers.
Among those understood to be in the firing line were aides of Theresa Villiers and Andrea Leadsom, who were both axed from the Cabinet on Thursday.
Cummings is said to have ended the meeting by saying: “I’ll see some of you next week.”
It is understood Cummings offered a partial apology over the remark at the latest gathering on Friday when challenged.
Former Daily Record journalist Davidson, of Edinburgh, told him he had been “out of order” and urged him to show more consideration to people who were younger.
The source said: “Dom’s treatment of some advisers at the previous week’s meeting was brutal.
“Lynn felt that he publicly humiliated the most vulnerable people in the group, who knew they were going to be soon out of a job.
“He was firing questions he must have known they couldn’t answer because it was on subjects they hadn’t been asked to prepare.”
Many special advisers felt unable to speak up over fears of losing their jobs, sources say.
Some hold ambitions to become MPs and cabinet ministers and do not want to risk their future by making powerful enemies.
Cummings, 48, became Johnson’s top adviser last July.
A month later, he fired former chancellor Sajid Javid’s aide Sonia Khan after he accused her of leaking information. Khan had her phone seized and was escorted from Downing Street by police.
She has started a claim for unfair dismissal and discrimination against the Government.
Her dismissal is considered to have triggered a breakdown in relationships between Johnson and Javid, who resigned his post last week after he refused to sack his advisers.
No10 declined to comment.
