"The Post Office is owned by the government, through the Department for Business, Energy and Industrial Strategy (BEIS) and UK Government Investments (UKGI), however, the Post Office Ltd Board has responsibility for the operations of the Post Office" [0]

And "The Department of Business Energy and Industrial Strategy holds government responsibility for postal affairs, including the Post Office" ... "the Post Office Ltd remains accountable to the government" [0]

[0] https://researchbriefings.files.parliament.uk/documents/CBP-...