"In these times in which our world appears to be dominated by the mundane and passionless, whether in the guise of Westlife, the Big Brother house or our politicians," reasons Mark Steel, "it may be a comfort to know the people who mattered the most were all splendidly passionate and endearingly mental".

These "endearing mental" personalities are the focus of his semi-educational series of lectures, which started out on BBC Radio Four in 1999.

Originally subtitled, "A series of lectures about Englishmen who changed the course of history," the show kicked off with a profile of Oliver Cromwell, and established the format wherein our host would provide a wittily persuasive argument for the importance of his chosen subject, spinning off into various idiosyncratic sketches.

Over three years on radio, the brief changed slightly to become "a series of lectures about people with a passion", as the likes of Aristotle, Che Guevara, Hannibal and Napoleon Bonaparte came under the microscope.

Then, in 2003, the lectures transferred to BBC Four, in a co-production with The Open University. Here Steel gloried in representing the historical personalities in modern day contexts, including - as he himself says - "Lord Byron as Joe Strummer, Isaac Newton as Carol Vorderman and Darwin as the man who goes mad in Close Encounters of the Third Kind."

A generally successful translation, the TV version suffers slightly, lacking the radio show's spontaneous, off-the-cuff feel. Nevertheless, it's been bolstered by an array of famous guests, including Mark Lamarr, Bob Monkhouse, Linda Smith and Ainsley Harriot.