The UK post office was privatized in the middle of the period in question, so your assertion is half-true. Of course, even as a private entity it retains an aura of state authority which may have swayed perceptions of juries. https://en.wikipedia.org/wiki/Royal_Mail#Privatisation
No, this is not accurate. The Post Office was split from Royal Mail; Royal Mail was privatised while the Post Office remained (and still remains) in the public sector.