In June, Mr Cummings told political aides that a “hard rain is coming” as he vowed to overhaul an “incoherent” Cabinet Office, creating a smaller centre of government with a different culture.
But there is growing criticism that officials, rather than ministers, are taking the blame for mistakes in the response to the coronavirus pandemic.
The latest was Jonathan Slater, the top civil servant at the Department for Education, who was sacked last week over the summer exams fiasco – even as Gavin Williamson survived as education secretary.
Mr Johnson said: “Simon will make a fantastic cabinet secretary and head of the civil service. His years of experience at the heart of government and working for the royal household make him ideally suited for this crucial role.
“I would also like to thank Mark Sedwill for his outstanding service to the government and the country as a whole. After serving for decades with great distinction, I believe he has earned the gratitude of the nation.”
Mr Case said: “I have seen how much hard work is being done by the civil service to support the government and our country through unprecedented times.
“It is a privilege to come into this role to lead a service that is working day in, day out to deliver for people right across the country.”
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