Terrance Dicks joined Doctor Who as junior assistant trainee script editor in 1968, when they were making The Web of Fear and desperately trying to make a roaring Yeti sound less like a flushing lavatory. He worked on the show during the end of the Patrick Troughton years, and co-wrote The War Games, Troughton's last show, with Malcolm Hulke. He stayed on as a script editor for the whole of the Jon Pertwee period, and left to write Robot, the first Tom Baker story. (This was in accordance with an ancient Who tradition, which he'd just invented, that the departing script editor writes the first show of the next season.)
In the years that followed he wrote a handful of Doctor Who scripts, finishing in 1983 with The Five Doctors, the programmes twentieth anniversary special.
In the early 1970s he was in at the very beginning of the Doctor Who novelisation programme and ended up, more by luck than judgment, writing most of them - seventy something in all. He has since written a number of Doctor Who 'originals', including Exodus, part of the opening Timewyrm sequence published by Virgin, and The Eight Doctors, the first original novel published by BBC Worldwide.
He has written two Doctor Who stage plays, one a flop d'éstime (great reviews, poor audiences), the other a bit of a pantomime but a modest touring success. He has also written about a hundred non-Who books, fiction and non-fiction for young adults, but nobody ever asks about them.
In over thirty years with the Doctor he has grown older, fatter, greyer and grumpier. But not noticeably wiser.