British people love long-lasting traditions like the Monarchy, Parliament or drinking a "nice, cup of tea". The Archers is one of them -the longest-running radio soap-opera in the world- The Archers is "a contemporary drama in a rural setting", called Ambridge, which has been running non-stop since 1951 on Radio- 4, the main talk channel on the BBC. It has over 5 million listeners every day, one million of them via the internet, according to Wikipedia. Here you can find a synopsis of the soap, and a lot of background information (Link B2).
On The Archers web page, you can find videos, clips, podcasts, a list of characters, a blog, and, of course, you can listen to the latest episodes on the archive. These audios and videos, without subtitles, are problably suitable for C2 students.