The giants Vincent and Goram were probably once as familiar to Bristolians as Cinderella or Little Red Riding Hood. There are various versions of the story which originated in medieval times (or perhaps earlier) of how the two giants, Vincent the hard-working and conscientious one and Goram the slob, carved out the Avon Gorge, the great port of Bristol's link to the sea. In some versions, they were competing for the affections of the fair maid Avona, who came from Wiltshire, apparently.

Of course for graphic purposes you can't have giant-sized giants. We dealt with this by making them rather more human in scale and saying they'd been diminished by the way they were fading from popular memory. Simon picked up on this very nicely by showing a massive human figure on faint outline on the rockface of the Gorge on the comic's front cover.

The giants are accompanied by a creature which (as far as I know) does not feature in any specifically Bristolian mythology but it crops up in ancient stories from all over England and Wales. This is a very mysterious animal related to worms and serpents and, of course, to dragons. It features in Anglo-Saxon mythology and is closely associated with the kingdom of Wessex. Modern-day Wessex regionalists have a flag featuring a golden wyvern.

It generally tends to symbolise envy, revenge and plague and its breath is supposed to be foul and pestilential. All in all, its west country connections are very strong, and in any event it's too good NOT to use. We see it early on in the story as a stone statue before realising that it can come to life.

The most important character in the story is Scipio Africanus, the African slave/servant who is buried in Henbury churchyard. Scipio is hugely important in Bristol's history since his is one of the few known burial places in all of England of an African from the time when Christian Englishmen traded in slaves.

I had already used Scipio in my novel 'Things Unborn' (Earthlight, 2001); this is set in the early 21st century in a parallel world where people who died prematurely in the past are coming back to life all over the place. It's basically about the tensions between people of different backgrounds and different values who have been thrown together having to evolve a functioning society and a way of co-existing. My original intention had been to use Scipio as a fairly minor character in the novel, but as the project progressed I found him taking an increasingly dominant role. By the final draft he had become the hero. This was for a variety of reasons, the most important being that he was the most interesting character as someone who had once been a slave but had now found a useful niche - as a police officer - because he understood better than most of the other characters in the story how difficult it can be to fit into an alien society.

I knew early on that Scipio would play an important role in St Vincent's Rock, but for completely different reasons, all to do with his importance to Bristol both historically and mythologically.

Of the real Scipio, we know nothing more than what is carved on his gravestone at Henbury. He was a slave or servant in an aristocratic household, his real name was replaced with a joke name from the white man's antiquity, he was evidently treated with some affection, he became a Christian and he died at about the age of 18. That's it.

If you visit Scipio's grave in Henbury churchyard you'll usually find that someone has left flowers. This may be one person making regular visits, but it's more likely several people. It has become a minor place of pilgrimage.

As modern multiracial, multicultural Bristol struggles to come to terms with the vicious trade of its merchant forebears, Scipio reminds us that, actually, the city has been multiracial for hundreds of years. As an individual who, unlike Vincent, Goram and Avona, really did exist, he serves as a bridge between historical fact and myth.

What we were trying to do here, is point out that Bristol's myths are not confined to fairy tales about giants digging a channel to the sea. Myths are all around us all the time in the tales we tell one another at work or in the pub, and a lot of them have some sort of basis in fact. When it comes to actual history, Bristolians tell one another more tall tales than most; of how the cellars of city-centre pubs were once slave warehouses, of how there were auctions on Blackboy Hill, of how such-and-such a pub was once run by Long John Silver (who many people don't seem to appreciate was a fictional character). There are stories about the Blitz, about the night Eddie Cochran played his last ever gig here, how Cary Grant went to school here, or lived in that house over there ...

Some of these myths are alluded to or mentioned in the story. I wanted our mythological heroes came to life from time to time to help Bristolians out, and figured that a scene set in the Blitz with them saving the life of Ben's grandmother might be worthwhile. Bristol suffered terribly from German bombing raids during the war. Hundreds of people were killed, thousands more maimed in body and mind, and several areas of the town were demolished for ever. While the effect of the Luftwaffe on the modern city's geography is visible to those who care to look for it, most of us don't notice it very often. We take the 1950s Broadmead shopping centre, or the skeletal ruins of churches, for granted.

As Simon and I were thinking about this sequence, in which a cinema is bombed, he suggested there should be a poster to show what film was showing at the cinema. I looked up the biggest films from the period and realised it had to be 'His Girl Friday', a stunning, sparkling screwball comedy from 1941 featuring one of Cary Grant's finest performances as Walter Burns, a ruthless newspaper editor.

From that we had no trouble figuring out the name and appearance of the editor of our version of the Evening Post.

A happy accident? I don't think so. Just a reflection of the amazing richness and complexity of Bristol's histories and tall stories.

The theme? Oh well, that was there all along. It's all there being hammered home on page one; a city whose inhabitants ignore its history and myths is a city without a soul. Further on in the story, we have Scipio saying,

"Now we're being killed off. By electric lights and roads and cars and television. By humanity's need to live in an eternal present, with no past and no future."

If Bristol is just a place where people work long hours to acquire and spend money, if all we do for kicks is hang out in designer shops, or listen to bland flavour-of-the-moment pop music or watch glossy movies made by and starring Americans, then the place where we live will become the same as everywhere else. Bristol will have sold its soul to a global monoculture driven by money. As it is, Bristol has a long and incredibly rich set of stories of its own which a little 22-page comic can only begin to hint at. A lot of that history is violent and shameful, but a lot of it is courageous and inspiring, too. In any event, even shameful history is better than having no history at all, and it's one good reason why Bristol deserves to be European Capital of Culture a lot more than some places we could mention.