For me the early-mid 70's were the peak of UK sit-coms. The 5 I'd single out are...
Porridge,
Yes Minister/Prime Minister
The Good Life
Faulty Towers
Reggie Perrin.
All the above have dated well, and are still funny (to me at least) today, even though some have some language which is seen as 'dubious' by todays standards. All the above were BBC shows. ITV stuff always seemed to be more akin to slapstick that didn't require the brain to be engaged which I'm not really a fan of.
Aren't most of those more late 70s onwards?
They all work well because they have easily recognisable characters, who behave consistently. None of them are meant to be likeable; some of them are truly dreadful people.
They were all tightly written and edited, by no more than a couple of people. I suspect those two things are intimately connected.
Each series is short in traditional British TV style.
Porridge is 74-77
Faulty Towers 75-79
Good Life 75-78
Reggie Perrin 76-79
Yes Minister 80-82.
So I'll concede on Yes Minister, but the 'golden era' appears to start between 74-76. All but Yes minister were done and dusted by the time Thatcher got into power (1979).
Personally I think comedy works when you can see yourself in the situation - either as one of the characters or you know someone who is such a character. You have to be learning something too, not just letting it wash over you. I could never really get into Hyathcinth Bucket, or The Office, or The Young ones because I don't really care to know people like that. I'm not saying that these aren't funny to some who do know those characters, just not me.
That's also where I think stuff like Alf Garnett can fall down. Some parts are undeniably hilarious, but it's too easy for certain parts of the audience to empathise with Alf rather than understand the real message that I think the writers and Warren Mitchel were trying to convey. And the more inflamitory the subject, the more of a problem that is.
As for Mr Skrunts second list - not for me. Mostly run of the mill stuff that goes in one ear and out the other. Rising Damp perhaps the exception there, but for me Beckinsale was better in Porridge, and Rossiter was magnificent as Perrin.