When the stories were collected in books, an even stranger thing occurred. Literary figures high and low, not noted comics fans, adored them. "Sandman is a comic-strip for intellectuals," Norman Mailer thundered. Stephen King called it "a treasure house of story".
Pulitzer Prize judge Frank McConnell cursed Gaiman's nationality, his bar to nomination. And as Gaiman's acclaim grew, so did his audience. The Sandman sold 1.2 million a year. By its end, Gaiman sold more comics than Superman.
He had become quietly famous, powerful. DC ended The Sandman at his request, with regret. His displeasure was worth more to them than a million lost sales. Other, more experimental comics (Violent Cases, Mr Punch) have sold well, adding to his status. He has toured America like a rock star, Internet subscribers feverishly ask if he is God. The Sandman is to be filmed by Pulp Fiction co-writer Roger Avary. And Neil Gaiman has had enough.
"I'm the comics writer that people who don't read comics have heard of," he says, poised on an armchair in a Notting Hill office. "I didn't like it. It made me pleased that Sandman was coming to an end. I think I got out just in time." What Gaiman has had enough of is the place where The Sandman has put him. He knows that there are other writers in comics as good as he is, who've been denied his freakish critical acclaim. And he feels, on the other hand, that his success has left him taken for granted inside comics' narrow world. He compares himself with Nick "Three Oscars" Parks, once thought of as an interesting animator, now too famous to be thought of at all. By some trick of fate, Gaiman's name has come to dwarf the medium he works in. He is Gulliver in Lilliput, horribly unique. It's a situation that has forced a simple, startling decision. "I expect to spend a couple of years doing other things," he says quietly. "And go back to comics when people have forgotten me."
It's equivalent to Tarantino quitting cinema. How can he? Isn't comics what he does ? "Story-telling is what I do," he says. "Comics are my first love. But one reason why I'm happy to stop is so that we can stay in love. I never got to the point in eight years when I got up in the morning and thought, 'Oh fuck, I have to write Sandman.' In another year I might have done. There was this bizarre temptation to carry on. We've got this thing that is an enormous commercial machine now. One could see that there was going to be a temptation to keep going just because of that." His tone changes to muttering calculation. "Could I do another five issues of Sandman? Well, damn right. And would I be able to look at myself in the mirror happily? No. Is it time to stop because I've reached the end, yes, and I think I'd rather leave while I'm in love."
Coming back might be harder. "I've been told that once you go away, you never come back as good," Gaiman admits. "I think the reason it may be true is that the burning desire to prove something is gone. I do not have a desire to get in there and write a really good comic to show people that" - in a voice of childish wonder - " 'Look! I can!' I've already done that, I've written comics as good as anything in the medium." But what if other avenues didn't work out? What if he had to write comics? "I don't want to retreat into the safety of comics. I think it would be a waste of a life if in 10 years' time, unable to do anything, I wound up going back and writing a Sandman that was a sad copy. At this point in time, I would rather write a bad Broadway musical than a really good comic. At least it would be forward motion."
For the moment, Gaiman's gamble is paying off. His first teleplay, Neverwhere, starts on BBC2 next week. The story of a Yuppie who falls between the cracks into a secret, magical London, even its making has met Gaiman's quest for new experience, taking him into sewers and secret tunnels, fresh, hidden places. He recently watched as Piccadilly Line commuters glimpsed a dinner party floating in mid-air in a forgotten tube station, an image they can barely have believed, brought to life from his imagination by Neverwhere's crew. "I feel like I've fallen through the cracks myself," he says. His script has attracted a cast that includes Hywel Bennett and Freddie Jones. Brian Eno has added the score. The BBC's head of drama has compared Gaiman's promise to Dennis Potter's. A radio play, Signal to Noise, has also been recorded, for Radio 3. And for a little while, the comics remain. The final Sandman, about finishing a story, has only just left the stands. Gaiman felt scared when he wrote its last words. Then he went to sleep. He had wild dreams. How does he feel now? "Like I've just left school."
n 'Neverwhere' begins a six-week run on BBC2 at 9pm next Thursday. The penultimate 'Sandman' collection, 'The Kindly Ones', is published by Titan Books on 20 Sept