CLOWES: There’s a book that came out more than ten years ago − a 50th-anniversary index of the members of the National Cartoonists Society. It’s a book of photos and short bios of hundreds of old-time American cartoonists, and for some reason a few “younger” − I was thirty-seven at the time − non-members, such as myself, were included.

There are dozens of photos of these old codgers smiling with these stupid grins on their faces. But you can see the sadness underneath. It’s such a grim document. My friend [and fellow cartoonist] Chris Ware told me he had to actually hide his copy of the book, because he can’t bear to look at it.

QUESTION: What did you both find grim about it?

CLOWES: All these lives spent behind the drawing board; decades on a daily strip that no one remembers.

‘His testimony offers a compelling argument against conspiracy theories. He spent between five and seven years roaming the corridors of power like the Invisible Man, wandering into Pentagon offices, rifling through files, and he found no particular smoking gun about anything. He unearthed nothing to suggest a US involvement in 9/11, nothing to suggest a UFO cover-up. Nothing, he told me, except two things…’