I only watched the first series, it's classed as dry humour, with a touch of sarcasm, and has dealt with some important topics, so I thought it not only funny but clever.
Irony, and sarcasm are the bedrock of British humour, the delivery is usually of a deadpan nature meaning that there is no neon signs to tell you "this is a joke." There also requires a lot of reading between the lines, subjects of humour typically involve mockery of failure. Joking about your dead grandfather or your cousin's dyslexia is completely acceptable in British comedy if done in jest. This type of humour teaches you not to take yourself too seriously through its strong theme of self-deprecation, and does not encourage over-sensitivity or self entitlement.
Hence, British humour may not transfer to a foreign audience and vice versa.
