Which British television series is set in the offices of PR company Mellish McCabe?

Answer 1

( I know a series set in Prentiss McCbe which details are as follows:)
Absolute Power is a British comedy series, set in the offices of Prentiss McCabe, a fictional public relations company (or 'government-media relations consultancy') in London, run by Charles Prentiss (Stephen Fry), and Martin McCabe (John Bird).
It started in 2000 as a Radio series. Its name is taken from a quote by the historian Lord Acton that "power tends to corrupt, and absolute power corrupts absolutely."

Answer 2

Don't you mean Prentiss McCabe? That was "Absolute Power" starring Stephen Fry and John Bird.