This past year or two I've been revisiting what you might call my cultural roots. Because I was distracted almost daily by treatment for a wounded foot and unable to work much, I began re-reading the PG Wodehouse, Edgar Rice Burroughs and Sexton Blake stories I enjoyed as a kid. From these I went on to movie and TV favourites, some of which proved to be pretty dreadful. Among them were Hopalong Cassidy, The Prisoner – and Doctor Who.

I have to admit that, while I watched most of his episodes as the Doctor, I disliked William Hartnell, the first occupant of the Tardis, who barked with the authority of his sergeant from The Army Game. Patrick Troughton, the second Doctor, brought an absent-minded quirkiness to the character which stayed with him at his best. Jon Pertwee took him back to his more authoritarian mode and then came the glory years of Tom Baker – reasonable complexity, wit and an aptitude for ad libbing which was wonderful to watch but must have been murder for the other actors.

Every Saturday was organised around the Doctor's adventures in Time and Space, with plenty of hiding behind available furniture (you couldn't actually get behind our sofa) and there was even a visit to White City to meet Tom Baker and the Daleks in real life. I remained unimpressed by 2001, A Space Odyssey, but I'd go to considerable lengths not to miss an episode of The Brain of Morbius.

I think I like the character mostly because he remains largely unrationalised and ambiguous. Russell T Davies understood this and made it the Doctor's most attractive quality. All lasting characters, from Richard III on, have at least a duality which makes them appeal to new generations. Like Arthur, Guinevere, Lancelot and Becky Sharp, the Doctor is infinitely interpretable.

About the only real science fiction I've written since the 1960s was The Dancers at the End of Time stories, all done in the 70s. They're comedies set in the distant future with a nod to the fin-de-siècle of Oscar Wilde, HG Wells, Ernest Dowson and The Yellow Book. Both comedy and SF depend on compression and exaggeration and are very often entertaining when combined. There's a long tradition of it: even Wodehouse wrote a funny, futuristic story early in his career (The Swoop! or How Clarence Saved England). In the SF magazines, writers such as Henry Kuttner, Robert Sheckley and L Sprague de Camp were best loved for their comedy. Douglas Adams, of course, hit the jackpot in the 1970s with The Hitch-Hiker's Guide to the Galaxy. Davies and his writers realised this when the Doctor made his comeback some five years ago with Christopher Eccleston and then David Tennant in the role. Both actors have a talent for comedy and melodrama. The plots became increasingly complex, playing with ideas of time and space, and I became an addict again.

Eventually, my well-springs replenished and my foot on the way to healing, Doctor Who became almost the only escapism I allowed myself. Though I have written little SF recently, I have begun a series of autobiographical novellas and novels in which I examine my taste for romance and fantasy: my characters are thinly disguised versions of writers and others associated with New Worlds magazine in the days when we tried to find new approaches to literary novels by using the methods and ideas of science fiction.

This trilogy of books, featuring a version of myself in a somewhat re-invented London, is intended to examine the appeal of fantastic adventure stories of the kind inhabited by my most popular character, the albino sorcerer-prince Elric of Melniboné. Elric is my Sherlock Holmes – a protagonist better remembered than most of my others, but in my case not the burden Conan Doyle felt Holmes to be. I'm very grateful that Elric continues to keep me in my old age, together with other stories I've written set in my "multiverse", a term I invented (or reinvented, since I wasn't originally aware that William James coined it to describe the many worlds our minds inhabit) in 1962, for a near-infinite system of parallel worlds in which subtly different versions of our own universe exist simultaneously. The term caught on well enough to be used for a variety of purposes in popular fiction and theoretical physics and was incorporated into the lexicon of Doctor Who. There's nothing unusual in this. Terry Pratchett said generic fiction is a big pot from which one takes a bit and adds a bit. I'm flattered that some of my ingredients became staples, but it's always a pleasure to use what was once a private vocabulary in another medium.

When I was first offered the chance to write an original Doctor Who novel I hesitated. I felt I'd had enough fun and should settle down to the autobiographical stuff I'd mapped out for the next year or two. Then I realised that not only might I enjoy writing an original adventure, I could also take a look at what a character who has become part of our national folklore has come to mean. I could do, in fact, what SF does best for an intelligent, knowing audience. So I told my agent to go ahead and draw up the contract.

Now the vast potential of what I can write is beginning to dawn on me. Far from thinking in terms of fun I've become a little scared. All time and space is open to me. I have to mix comedy and melodrama while telling an epic adventure story featuring a complex protagonist capable of ranging across the entire multiverse. I'm increasingly overawed as I consider what I must live up to. Hardcore fans are already questioning my qualifications. I can only hope I'm equal to the job.