The government says the decision was made with mutual consent – but the Post Office says he was asked to go.
The Post Office chairman has stepped down amid ongoing tensions after the Horizon IT scandal that saw hundreds of sub-postmasters wrongly convicted.
Business Secretary Kemi Badenoch said she and Henry Staunton parted ways with mutual consent, as the Post Office was under heightened scrutiny and she “felt there was a need for new leadership”.
But the Post Office said in a statement that he had been asked to leave.
An interim chair is expected to be appointed shortly.
Mr Staunton had been in the role at the state-owned company since December 2022.
As part of the role, advertised with an up to £150,000 salary, he had been tasked with leading the board of directors and working to the right the wrongs of the Horizon dispute.
Prior to this, he had worked on the board of companies ranging from ITV to WH Smith.
The Post Office spokesperson said: “On Saturday afternoon, the Post Office was informed that the business and trade secretary had asked Henry Staunton to stand down as chairman of the Post Office.
“We have been advised by the government that they will appoint an interim chairman shortly.”
The government has not responded to requests from the BBC to provide a reason for Mr Staunton’s dismissal.
It said a recruitment process will be launched in due course.
Sky News, which first reported the story, said an insider claimed there had been several sources of tension between the Post Office chairman and the government in recent months.
But sources said Mr Staunton’s exit was not directly related to the Post Office scandal.
Among the tension, was reportedly a row over the best candidate for the appointment of a new senior independent director.
It comes as the Post Office is reeling from the fallout from the Horizon scandal, which has been called the biggest miscarriage of justice in UK history.
More than 700 sub-postmasters and sub-postmistresses were prosecuted between 1999 and 2015 after faulty accounting software Horizon made it look as though money was missing from their shops.
Many of those affected were financially ruined.
The issue recently came to wider public attention after it was depicted in an ITV drama. and public anger led to the former Post Office boss Paula Vennells handing back her CBE.
Senior figures from the Post Office and the technology firm Fujitsu, which developed the Horizon software, are currently facing questions at a public inquiry over what happened.