EXCL John McDonnell and Len McCluskey in 'explosive' clash over Labour shake-up
John McDonnell clashed with Len McCluskey in the wake of a major shake-up of Jeremy Corbyn's office, PoliticsHome has learned.
The pair met last Thursday to discuss Labour's plans for the next general election.
But it is understood that the conversation "erupted" after it turned to changes made to the senior team around Mr Corbyn.
Just days before, Karie Murphy, the Labour leader's chief of staff and a close ally of Unite boss Mr McCluskey, left his office to take up a new post at the party's HQ.
She is keeping her title, but her role will be taken over by former civil servant Helene Reardon Bond, who was recruited last week.
Amy Jackson, Mr Corbyn's political secretary, also left his parliamentary office, along with trade union liaison official Joe Bradley.
Labour sources have claimed that Mr McDonnell - whose close friend Lord Kerslake informed Ms Murphy of her change of role - was behind the reorganisation, although that has been denied by his aides.
The Shadow Chancellor is known to be at odds with many of those close to Mr Corbyn, particularly over Labour's approach to Brexit.
He has said he is open to the possibility of holding a fresh EU referendum before the next election, something the Labour leader opposes.
On Mr McDonnell's meeting with Mr McCluskey, one source said: "The pair of them erupted. It was explosive and their differences were not resolved."
A source close to the Shadow Chancellor confirmed that the meeting took place, but insisted it was the latest in a series of routine discussions they have been having on election planning.
A spokeswoman for Mr McCluskey refused to comment.
Meanwhile, PoliticsHome has also learned that morale has plummeted in Mr Corbyn's office amid claims that Mr McDonnell is behind plans for a complete overhaul of the way it is run.
Leaked emails seen by Sky News revealed that Lord Kerslake will carry out "informal" interviews with 37 members of staff.
One insider said: "It's like nothing I have ever experienced before. John McDonnell has really had his fill of a lot of the people around Jeremy."
Following Ms Murphy's removal from Mr Corbyn's office last week, a Labour source insisted she had not been demoted.
"As we gear up for a general election, Labour is bolstering our team to take on the Tories and ensure a Labour government can hit the ground running with our programme to transform the country," they said.
"Karie Murphy will strengthen the election operation at Labour HQ to drive the general election campaign and Helene Reardon Bond will bring her experience and expertise to the leader’s office to step up our preparations for government."