Nick Read, the Post Office chief executive, has announced his resignation days before the Horizon inquiry enters its final stage.
Mr Read, who has led the scandal-hit postal service since 2019, will step down from his role in March.
Neil Brocklehurst, who joined as the interim chief operating officer in June, will serve as acting chief executive while the Post Office searches for a permanent replacement.
It comes after Mr Read stepped back from his front line duties over the summer to focus on preparing for the seventh stage of the inquiry, which will examine practice and procedures at the organisation, as well as executive pay.
The Post Office said Mr Read welcomed the opportunity to testify at the proceedings, which are scheduled to begin on Monday.
Mr Read was appointed as chief executive with a goal of modernising the Post Office. He subsequently oversaw a £58 million settlement to a group of 555 postmasters led by Alan Bates, though the claimants were left with only £20,000 each after hefty legal costs.
Mr Read said: “It has been a great privilege to work with colleagues and postmasters during the past five years in what has been an extraordinarily challenging time for the business and for postmasters.
“There remains much to be done for this great UK institution, but the journey to reset the relationship with postmasters is well under way and our work to support justice and redress for postmasters will continue.”
Nigel Railton, the interim chairman of the Post Office, said: “On behalf of the board, I would like to thank Nick for his commitment and hard work in leading the business over the past five years.
“It has been a challenging period for the Post Office and its postmasters, and Nick has been instrumental in navigating the business through this while beginning the important process of cultural change. We wish him all the best for his future endeavours.”
Mr Read’s resignation comes at a turbulent time for the Post Office, which is facing fierce scrutiny over its role in the Horizon scandal.