Loved this lot as a kid and still do today. Extremely clever wit whereby they take two unfunny scenarios/subjects and make something funny out of it, like the Welsh miners sketch. Welsh mining is not particularly funny, and neither is Greek Doric architecture, but put them together and you get comedy gold.
This pattern repeats throughout, and is what makes MP continually fresh, original, and appealing. Compared to more present day sketch shows they rarely repeat skits, or characters so a whole lot of thought and unpredictability goes into each episode.
They also take ordinary scenarios and push things to the extreme (silly walks, stereotypes), or switch roles (miner son, poet dad).