The civil service's current longest-serving permanent secretary, Sir Nicholas Macpherson, is to leave his job as the Treasury's top official at the end of March, it has been announced.
Macpherson was appointed perm sec at the Treasury in August 2005, and has served in the role alongside three chancellors – Labour's Gordon Brown and Alistair Darling, and the current incumbent at the finance ministry, George Osborne.
In a statement issued on Monday, Macpherson announced that he would be stepping down and leaving the civil service on March 31.
MPs: Nicholas Macpherson advice on Scottish currency union 'should not have been published'
HMT boss warns against shakeup of Treasury functions
"It has been a privilege to lead the Treasury through an extraordinary period," he said. "But after 31 years in the department, and having worked on 33 Budgets and 20 Spending Reviews, it is time to do something else while I still can.
"With the fiscal strategy for this parliament set and the economic recovery well established, now is the right time to stand aside and for someone else to guide the Treasury through the challenges ahead.
"I pay tribute to the remarkable energy, creativity, resilience and decency of the Treasury ministers and officials I have worked with."
Osborne heaped praise on Macpherson, describing the perm sec as "one of the outstanding public servants of his generation".
"He has been at the helm of the Treasury during the most difficult decade of modern economic policy making and his advice to me has always been intelligent, candid and discreet," the chancellor said.
"He will be sorely missed by the official team he has built up at the Treasury and ministers, like me, lucky enough to have worked with him."
According to the Treasury, the process for selecting Macpherson's successor will be announced "in due course", but the department says it intends to have a successor in place by April 1.
Including his lengthy stint at the top of the Treasury, Macpherson has spent more than three decades in the civil service, joining the organisation in 1985.
He has held a variety of roles at finance ministry, including as managing director of the Budget and Public Finance Directorate and before that as head of the Public Services Directorate.
He was also principal private secretary to Conservative chancellor Ken Clarke from 1994 to 1997.
Macpherson's departure is the second high-profile exit at perm sec level to be announced in the past month. In December, the Department for Health's most senior official, Una O'Brien, announced her retirement from the role.