The cabinet secretary, Sir Jeremy Heywood, Whitehall’s most senior civil servant, has been treated for cancer, the Cabinet Office has said.
Heywood, the prime minister’s top policy adviser, served in Downing Street under Tony Blair and Gordon Brown, becoming cabinet secretary under David Cameron.
In a statement on Friday, the Cabinet Office said Heywood was diagnosed with cancer in June and had treatment over the summer and early autumn. The treatment “went well” and the cabinet secretary was continuing to work.
“Throughout this period, with the full support of his doctors, Sir Jeremy has continued with his normal duties for the prime minister and cabinet, and as head of the civil service,” a spokesman said.
“He remains totally focused on those duties and we will be making no further comment on this private matter.”
Heywood has often been described as the most powerful person in Britain who is not a household name. He has been central to some of the most important decision-making of modern politics, including the lead-up to the Iraq war, the formation of the coalition government, and the preparations for and the aftermath of the EU referendum.
Prior to joining Downing Street, Heywood worked at the Treasury under Tory chancellor Norman Lamont and his successor Ken Clarke, followed by Brown after Labour’s 1997 election victory.
Downing Street said the Prime Minister was “kept informed throughout” Heywood’s treatment, which is understood to have been completed. A Number 10 spokeswoman said the cabinet secretary had May’s “full support”.
