Most of the time when I\u2019m writing the idea comes first. There\u2019s an idiom to twist, a play on words, some jargon that needs puncturing \u2026 But sometimes you just get an image in your head and you go backwards. Take for example this Trojan warrior in an office. Why is he there? What does he want? What\u2019s his viewpoint? The Trojan horse is a natural gag here, but I don\u2019t think I\u2019d have come upon it if I hadn\u2019t imagined this oddball scene first.