The physicist took to Twitter to ask the purpose of Boris Johnson’s top aide’s “revolution” of the civil service.
He said: “Could someone who supports the government tell me what the Cummings vision for the country actually is? I understand he wants a revolution in the civil service etc. etc. But I don’t know what it’s for. (Don’t mention Brexit btw because that’s been done so it’s no longer an aim).”
It comes as Sir Mark is standing down from his roles as Cabinet Secretary and the UK’s national security adviser as part of an alleged wider overhaul of the civil service amid reports Mr Cummings played a role in his departure.
The Prime Minister’s chief adviser is rumoured to have a difficult relationship with Sir Mark.
Mr Johnson praised Sir Mark following this resignation as head of the civil service.
He told Times Radio: “Sir Mark has given incredible service to this country. He came in at a very difficult time.
“He has seen the Government through all sorts of very tough stuff – changes in the premiership, an election, Brexit, dealing with the worst bits of the Covid crisis.
“He has got a lot more to offer and I am sure he will.”
The Prime Minister played down suggestions that Sir Mark had been the subject of a series of negative briefings in the media.
“I try not to read too much of the negative briefing. There is an awful lot of stuff that comes out in the papers to which I wouldn’t automatically attach the utmost credence.
“People brief all kinds of things into the newspapers. All I can tell you is Mark is an outstanding servant to this country and will continue to be so.”
But Sir Keir Starmer blasted the shake-up of the civil service.
The Labour leader told Sky News: “It seems to me obvious that the Prime Minister wanted to move the Cabinet Secretary and was determined to do so.
“Why you do so in the middle of a pandemic and a crisis instead of actually focusing on the crisis, is a question the Prime Minister needs to answer.”
Mr Cummings is said to have told a meeting of political aides last week that a “hard rain is going to fall” after insisting Whitehall’s shortcomings had been uncovered during the coronavirus crisis.