When young Justin Richards used to watch Doctor Who, there was no question of hiding behind the sofa. That wasn’t nearly safe enough. He left the room and hid behind a door, peering terrified through the keyhole as Patrick Troughton fought off an invasion of cybermen.

Yet these days Richards, now 46, is in the thick of the action as the writer and editor of a series of Doctor Who spin-off novels. This year alone he will preside over the disappearance of Balmoral castle and a perilous search for space-pirate treasure.

The first Doctor Who novels came out in the 1960s. There were just a couple at first, although if the Doctor was the time traveller he’d have us all believe, he could surely have predicted their great success. Now there are more than 250 original stories and 150 books based on the TV scripts. According to Guinness World Records, this is the largest number of books about a single character.

So what is the secret of writing a good Doctor Who story, apart from an inexhaustible supply of strange people in hoods and shadowy figures lurking in dark corners of the universe? Richards and some of his fellow writers – Terrance Dicks, Mike Tucker, Colin Brake and Steve Cole – will explain all at the festival on April 5.

For a start, resist the temptation to be too scary. “We stick to the same guidelines as the television series,” says Richards. “If it’s safe to watch on the telly, it’s safe to read it in a book. We’re not specifically writing for children, but need to be aware that children of 8, 9 or 10 will read them. So nothing too gruesome, not too much blood.”

Knives are very much discouraged, but guns are allowed as long as they are futuristic laser guns. “The stories should be dark,” says Richards, “but nothing too unsettling. And they should be quite funny. One of the hardest things is making sure that the humour doesn’t undercut the drama.” In his latest story, Martha in the Mirror, a character at an intergalactic peace conference announces, in Tony Blair fashion, that he feels the hand of history on his shoulders. A little joke for the grown-ups.

There is a team of 10 writers, but not all of them write full-time. They are paid a flat fee of £5,000 per book, with a bonus if a title sells more than 50,000. That’s about the average sale, says Richards, but bonuses are not unknown.

Authors have four months to turn out a story, but the Doctor might shove his sonic screwdriver into the works at the last minute. If the Doctor changes form on television – from a figure who looks like Christopher Eccleston, say, to a Time Lord who looks more like David Tennant – then some hasty rewriting must take place. “The first sight we had of David’s Doctor was a week before we had to get proofs,” says Richards.

On top of this, producers of the television series in Cardiff have a veto over the books. In one of this year’s stories, Revenge of the Judoon, the Doctor originally fought to save Balmoral and Edward VII with the help of Winston Churchill. Unfortunately the TV people liked the idea, and thought they might keep Winston in reserve for a future episode. So the author, Terrance Dicks, had to make do with a cameo from Arthur Conan Doyle instead.

These reasons might put off some big-name authors who have been linked with Doctor Who. Philip Pullman, JK Rowling, Anthony Horowitz and Stephen Fry have been mentioned. “I have spoken to a few big names,” says Richards, “and the attraction is obvious but there are reasons why they wouldn’t want to do it.”

So if you were expecting the Doctor to appear with a new assistant called Hermione Grainger, you might have to wait a bit longer.

OXFORD: WHERE TO STAY AND HOW TO BOOK

This year’s Sunday Times Oxford Literary Festival runs at Christ Church from Monday, March 31 to Sunday, April 6. To get a flavour of the festival, and to immerse yourself fully in the atmosphere of Christ Church, you can stay at the college, either by booking individual rooms for a starting price of £53 per night, B&B, or by taking advantage of our two-night festival packages, available exclusively to Sunday Times readers:

March 31-April 1: accommodation and breakfast at Christ Church, plus tickets to see Sebastian Faulks, Clarissa Eden, Oliver James and Rita Carter. Prices from £130.

April 2-3: accommodation and breakfast at Christ Church, plus tickets to see Seamus Murphy discussing Afghanistan with Anthony Loyd; the Penguin readers’ evening with Catherine Bailey, Jane Johnson and Jeremy Page; Dragons’ Den judge Peter Jones; Mark Tully; and Adam Mars-Jones talking to Margaret Drabble. Prices from £137.

To book your stay, call 01865 286848/286877 or e-mail festival@chch.ox.ac.uk.

BOOKING TICKETS

To book tickets for events at the festival, go online at www.ticketsoxford.com (24hr booking until March 31 at 10am) or telephone 0870 343 1001.

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