I'd had three westerns published by Robert Hale, in their Black Horse Western imprint. I was trying to decide on a subject for the fourth, when I remembered Paul Darrow saying that he'd love to star in a western; Michael Keating had quipped that he'd love to appear in a western with Paul Darrow. I couldn't cast Paul in a western movie, but I could use him in some way in a western novel. I knew that Tanith Lee had written a fantasy novel with characters based on Avon and Vila (Kill The Dead), so I figured I could use them in a western.
The result was Darrow's Law. Avon became the cynical sheriff of a small Wyoming town in the 1870's. He had been born to an aristocratic and wealthy Southern family, who had lost their money in the civil war, forcing Darrow to become a gun-toting lawman, rather than a lawyer, as he'd intended. I gave him Hugh Keating as his deputy. Like Vila, he's a gambler, and a self-confessed coward. Unlike Vila, I made him the second son of an aristocratic English family, sent abroad for reasons never quite specified. The two lived and worked together, with a love-hate relationship that gave me the opportunity to write some great dialogue.
Darrow's Law became the first of a series, as I had so much fun writing about the characters. They've grown and developed with each new book. There is no way the westerns could be as bleak as the TV series was - the format required the heroes to triumph. The more overtly cowardly and flustered version of Keating in the first book wasn't wholly approved of by the publisher, so through time he has come closer to being more of a traditional hero. He's the braver version of Vila that we see sometimes: the person who Vila might have been if he'd had a more stable background, and not got caught up with Blake and Avon.
Here I've reproduced the pages about the Darrow westerns from my pro-fic website, just as I wrote them when each book was published.