I randomly stumbled across these when channel hopping at 4am a month or two ago and was captivated. It's a great series and the format of having a panel of experts discussing a subject with only casual prompts from Rose is great (a format that works well with the BBC's In Our Time podcast too).
Also, PBS Closer to truth series - more philosophical in nature though, awesome nonetheless. <a href="http://www.closertotruth.com" rel="nofollow">http://www.closertotruth.com</a>