Anthony Horowitz is doing the media rounds again, probably with the intention of promoting his latest book. He's popped up on Question Time, CBBC Newsround and Radio 2's Book Club.

Horowitz has been accused of being a homophobe and a right-wing bigot, both of which he's denied. But with regards to the former accusation, let's look at the evidence.

In 2007 he wrote a piece for the Daily Mail in which he lamented "political correctness" had made it difficult for him to create new villains. It seems Horowitz thought that a villain, in order to convince, has to be gay or from some other traditionally disadvantaged group. As far back as the mid-1980's one of his nastier characters in an episode from Robin of Sherwood, Philip Mark, is gay.

But despite his obvious awareness that some people are gay, when he took part in a Q & A session for Newsround in 2010, his response implicitly denies the possibility that gay or bisexual people exist.

The final, and most convincing evidence comes from a 2013 TV debate about equal marriage. Horowitz appeared strongly opposed to marriage equality, stating that "a marriage involves man, woman and God." He claimed that wasn't his own view, but immediately went on to state that that is what it is. Just as confusing was his comment about tolerance; he took the view that we have forgotten how to tolerate intolerance.