The Chancellor has now seen three of his closest allies moved from their jobs. Against his wishes, Mr Blair moved Nick Brown from the pivotal job of Chief Whip to Minister of Agriculture last July.
Last month, Geoffrey Robinson - the Treasury minister closest to Mr Brown and regarded by the Chancellor as his "wise uncle" - was forced to resign after a series of allegations over his business career before he became Paymaster-General.
Now Mr Brown is to part company with the press secretary who has assiduously - and sometimes over-zealously - reshaped and built up his image for the past five years.
Mr Brown may have finally judged that his spin-doctor's continued presence might have stretched relations with the Prime Minister to breaking point.
Mr Blair was justifiably irritated that "Mr Brown's allies" - presumed to be Mr Whelan - described the Chancellor as the managing director who ran the Government and Mr Blair as the non-executive chairman, a kind of smiling front man.
A member of the Blair camp said yesterday: "There can only ever be one Prime Minister. Gordon has got to learn that."
Now ministers hope Mr Whelan's departure will enable Mr Blair and Mr Brown to draw a line under their past differences, which stem from Mr Brown's disappointment that Mr Blair became Labour leader after John Smith died in 1994. They also believe it will be easier for Mr Brown to achieve a long-promised reconciliation with Mr Mandelson, whom he has not forgiven for backing Mr Blair in 1994.
"Gordon makes enemies; he always seems to want to give people a bloody nose," said a cabinet minister. With Mr Whelan no longer on the scene, ministers say they will find out how much of the Brown camp's aggression was due to the spin-doctor's style and how much he was merely acting on his master's orders.
Mr Blair's allies want Mr Brown to cement his relationship with the Prime Minister rather than build on his alliance with John Prescott, after their agreement to reassert traditional Labour values since Mr Mandelson's departure. "He has much more in common with Tony than Prescott," said one insider.
Friends insist Mr Brown will prove a loyal and dependable Chancellor, and can become one of the most successful this century.
Mr Blair and Mr Brown are well aware of the dangers to both of them: Baroness Thatcher's allies believe she never recovered from the resignation of Nigel Lawson as Chancellor after a series of battles between No 10 and No 11. A year later, she was forced out.
So Mr Blair and Mr Brown have every incentive to draw a line under the destabilising events of recent weeks. "Their relationship is either the rock on which the Government is built, or the rock into which the whole enterprise is shipwrecked," said an ally of Mr Brown.Reuse content