Watching the excellent BBC drama about how Coronation Street started (The Road To Coronation Street, I think) - no doubt it will come round again and you should watch it when it does - it struck me that a series set in an ITV company of the early 60s could be the British 'Mad Men'. It could have everything, actors, writers, money men, larger-than-life Jewish impresarios, in-fighting, intrigue over advertising accounts, brushes with the ITA etc.etc. I think Granada TV with the serial number filed off would be the best bet, as it is not Lahndahn, and ATV was a bit of an outlier as Birmingham was really an outpost of the ITC empire.
Doubt something like this would get made with the current techno-economic paradigm of British TV though. Shame.
(*) Personal communication (see, I have been reading academic books again, have I mentioned how much footnotes saying 'personal communication' pisses me off? I'm sure I have. What is the point, clearly you have spoken to the person, you don't need a footnote.