Five decades doesn't mean much to a time traveller, but after fifty years, the Doctor is still a mystery.

Radio 4 Extra doesn't have all the answers, but we can shed a little light. Not just a TV phenomenon, Doctor Who has also taken us into strange new sonic realms and the written word. Mark Gatiss examines the Target novels, which offered a glimpse into those early stories before video. We hear from surviving cast and crew of the original pilot episode, the people who gave the show its unique sound in Dance of the Daleks, and finally we catch up with Susan - the Doctor's Granddaughter, last seen on 22nd-century Earth.

In between, John Lloyd, AL Kennedy and others who recall those monochrome early years examine what makes them so special. Hosting it is Tracy-Ann Oberman, not only a star of Friday Night Dinner and Eastenders but a Doctor Who villainess in her own right.

Tracy-Ann Oberman is an actor and writer with an extensive variety of diverse credits; Big Train, Toast of London and Monroe to name but three. For Doctor Who fans she will be known as Yvonne Hartman - the woman who saw off Rose and set up Torchwood.