Sir Chris Wormald has been named as the new cabinet secretary and head of the civil service.

The 56-year-old, who will now advise the prime minister on key policy decisions, will replace Simon Case on 16 December after he announced he is stepping down for health reasons.

Sir Chris is currently permanent secretary at the Department of Health and Social Care, advising the health secretary on policy and managing the budget since 2016 – all through the COVID pandemic.

Politics latest: No 10 condemns ‘misogynistic’ Gregg Wallace comments

Sir Keir Starmer, who gave final approval for Sir Chris, said he “brings a wealth of experience to this role at a critical moment in the work of change this new government has begun”.

The decision to promote Sir Chris is the biggest of Sir Keir’s premiership so far, with the civil servant having overseen large-scale reforms of several government departments – something that will have appealed to the PM.

The prime minister said his “mission-led” administration will change the way government serves the country, which “will require nothing less than the complete re-wiring of the British state to deliver bold and ambitious long-term reform”.

“Delivering this scale of change will require exceptional civil service leadership,” Sir Keir added.

“There could be no one better placed to drive forward our plan for change than Chris, and I look forward to working with him as we fulfil the mandate of this new government, improving the lives of working people and strengthening our country with a decade of national renewal.”

Sir Chris said he was “delighted” to be appointed to the “privileged role of leading our talented civil service”.

“The government has set a clear mandate – an ambitious agenda with working people at its heart. That will require each and every one of us to embrace the change agenda in how the British state operates,” he added.

“So I look forward to working with leaders across government, to ensure that the civil service has the skills they need to deliver across the breadth of the country.”

Professor Sir Chris Whitty, chief medical officer, will head up the Department for Health while a new permanent secretary is appointed.

Sir Chris Wormald beat other senior current and former civil servants to the job, advertised with a £200,000 salary.

The other contenders were: Sir Olly Robbins, a former director-general of the civil service who was involved in Brexit talks, Dame Antonia Romeo, permanent secretary at the Ministry of Justice, and Tamara Finkelstein, permanent secretary at the Department for Environment, Food and Rural Affairs.

Some within Whitehall believe Sir Chris was a “safe choice” compared with the other options.

He steps into the shoes of Mr Case, 45, who was appointed in September 2020 and served four different prime ministers.

In an email to the civil service announcing his resignation in September, Mr Case said: “As many of you know, I have been undergoing medical treatment for a neurological condition over the last 18 months and, whilst the spirit remains willing, the body is not.

“It is a shame that I feel I have to spell this out, but my decision is solely to do with my health and nothing to do with anything else.”

Mr Case announced his resignation following a difficult few weeks for Downing Street during which damaging leaks and internal rows took over the narrative, with Sir Keir growing increasingly frustrated.

The top civil servant was said to have had a tense relationship with Sue Gray, Sir Keir’s former chief of staff who stepped down in October following accusations from some Labour figures about the party’s handling of ministers taking freebies.