While most members of Tony Blair's original inner circle have fallen away since 1997, one remains at the very heart of the Downing Street machine.
By Nick Assinder
BBC News Online political correspondent
The prime minister's closest confidante is almost certainly the former diplomat Jonathan Powell.
Powell joined Blair from Washington
And with the likes of Alastair Campbell, Anji Hunter and Peter Mandelson gone, if not forgotten, the tousle-haired, energetic Powell has become increasingly important to the prime minister.
Although Powell is five years the junior partner, the two men appear to be genuine political soul mates - neither are from the Labour tribe or have any apparent attachment to it, and both are fervent Atlanticists and modernisers.
As the Hutton inquiry proved, Powell has always had an unprecedented position in the prime minister's affections.
He has also provoked great suspicion in some quarters, particularly in the civil service.
The Hutton inquiry pitched him into the spotlight with the revelation he asked security chief John Scarlett to change parts of the now-famous Iraq weapons dossier because some of the language was "a bit of a problem" for Downing Street.
Most recently he was in the news again after he and Tory MP and Spectator editor Boris Johnson found themselves alongside each other on their bicycles and Powell said Gordon Brown was living a "Shakespearean tragedy" as he would never become prime minister.
But Powell is not a natural seeker of the media spotlight any more than he is comfortable in the Labour movement.
Scarlett agreed dossier change
The 47-year-old son of an Air Vice-Marshal, comes for a highly-influential family which includes brother Charles Powell (pronounced Pole) who was Margaret Thatcher's foreign policy adviser.
His other brother, Chris, is a leading ad-man who has also assisted the Labour party.
After studying history at Oxford and the University of Pennsylvania, Jonathan worked for the BBC and Granada TV before joining the Foreign Office in 1979.
He was working in the British embassy in Washington - where he had the opportunity of following Bill Clinton's presidential campaign - when in 1995 Mr Blair, then Leader of the Opposition, poached him to join his `kitchen cabinet' as his Chief of Staff.
When Labour achieved its landslide victory in 1997 Mr Powell, along with Mr Campbell, was given unprecedented powers to issue orders to civil
It was a move sanctioned by cabinet secretary Sir Robin Butler but caused much resentment in Whitehall.
One of his most successful jobs was as the prime minister's most trusted lieutenant in Northern Ireland peace talks.
But he has also played a crucial role in advising the prime minister on a host of policy issues making him, today, one of the most influential people in Downing Street.
Mr Powell has four children - two daughters by his partner, journalist Sarah Helm, and two sons from a dissolved marriage.