Something The Avengers did really well (especially during the Emma Peel era) was recognize the…
Something The Avengers did really well (especially during the Emma Peel era) was recognize the connection between conspiracy & affinity group. In almost every episode, some kind of plot is hidden behind a club or association for some particular topic.
In one, a private golf club is cover for terrorist training. In another, model train enthusiasts & senile retired military men are being manipulated by their butlers. We see a mensa-type organization turned via mind control, psychics (twice: first, real ones, then fake)… Cat fanciers get sold collectable collars that cause cats to attack by remote control. We see a ballet school with a lean-in-feminist reputation secretly run by a man who is trying to create an all-female terrorist force for his own gain.
Several times, we see the specific social facilities of the ruling class explicitly at the center: old universities whose impenetrable-to-outsiders traditions provide cover for fascist organizers, a guy who uses hallucinogens & impersonates the nanny that many key government figures were all raised by.
I think this was probably to keep the series colorful. Secret Agent / Danger Man had similar premises around the same time but was afraid to go wacky, so instead he went to different ‘exotic’ countries, but ultimately the show was very dull. (This is a mistake the creators learned from when the went on to create The Prisoner.)