Netflx doesn't have series four...it is, I think, fair to say that series four is exceptional. Reece and Steve are incapable of writing boring stuff, they just get better and better. Series four was pure genius, Dead Line blows minds, what the heck does series five have in store??Ooer, a live episode?! Got to give that a go!
I'm currently re-watching all the series on Netflix. These two have really honed their skills over the years and the writing is so tight now, it's amazing what they can cram into just 30 minutes.
The exact same thing happened to me where I work, Rerenny! Except in my case he was vaguely aware of the League of Gentlemen but had somehow never seen any of it! I said that he should probably start with LOG as it was a bit more accessible than Inside No.9! Weirdly, though, he had seen Psychoville but had no idea it was the same people.