Thanks for mentioning the radio series, what others are great?

I watched this program on the advice of a friend, but I wasn't too impressed to be honest. I thought it was OK, but not nearly as funny as my mate said. But I came on this forum to read what other people thought, and saw how people said the TV series wasn't nearly as good as the radio series (which I didn't know of, the Count was totally new to me when I watched the TV series), so I've tracked down series one of the radio show and from what I've heard so far (the first two episodes) it's hilarious!

It makes me want to track down the radio series of programs I do like, such as The League of Gentlemen (a brilliant TV program), and Tony Hancock. What other radio series, old or new, are really funny, please?