No. The Post Office is not a private company, it's a public limited company with the government as sole shareholder.
It was changed from a government department to a statutory corporation in 1969. It was then changed to a public limited company in 2000.
Furthermore:
- Post Office Ltd owns and runs Post Office Counters Ltd which runs the post office branches. This is the company that uses Horizon (since 1999)
- Royal Mail delivers mail to addresses, and owns the Postcode Address File. Royal Mail was separated from the Post Office and privatised in 2013. It has never used Horizon.
Horizon is an EFTPOS/accounting system, nothing to do with mail delivery. It was introduced to the Post Office in 1999 after Fujitsu/ICL were originally commissioned by government to build an accounting system for the Benefits Agency, and it was so awful and buggy the Benefits Agency rejected it, so the government asked them to retool it for the Post Office.
It's the other way around here; the Post Office is effectively a government department, cosplaying as a commercial business. It has never posted a profit. It's up to the government to bail it out, every time. It's controlled at arms length by a body called UK Government Investments (UKGI) who crack the whip at it and try to ensure "value for the taxpayer".
The rest of the UK government is capitalism on stilts, and is forever outsourcing everything to the private sector. There was a scandal when the outsourcing firm Carillion went bankrupt - we learned that the cleaners in Parliament were under four layers of subcontracting - i.e. four sets of middlemen taking a cut between the government paying for cleaning Parliament and the people who actually do the cleaning. One of those middlemen was Carillion, which had just paid £79m of dividends to investors and then collapsed with £7000m in liabilities and £29m cash. That's because capitalism is perfectly efficient, and it's not just a bunch of crooks cooking the books to appear to be perfectly efficient, right?
It was changed from a government department to a statutory corporation in 1969. It was then changed to a public limited company in 2000.
Furthermore:
- Post Office Ltd owns and runs Post Office Counters Ltd which runs the post office branches. This is the company that uses Horizon (since 1999)
- Royal Mail delivers mail to addresses, and owns the Postcode Address File. Royal Mail was separated from the Post Office and privatised in 2013. It has never used Horizon.
Horizon is an EFTPOS/accounting system, nothing to do with mail delivery. It was introduced to the Post Office in 1999 after Fujitsu/ICL were originally commissioned by government to build an accounting system for the Benefits Agency, and it was so awful and buggy the Benefits Agency rejected it, so the government asked them to retool it for the Post Office.