Pollux writes:

Did you know that if you place the four Anniversary New Yorker covers together, this creates a large composite image of Eustace Tilley? When I wrote about the covers a few days ago, this had escaped my attention.

It wasn’t Dan Brown (or his hero Robert Langdon) who have told me. You can read about this hidden image at the blog Kempa.com.

Adam Kempa, the blog’s creator, has cleverly, and helpfully, created an overlay of the four covers to reveal the subtle outlines of Tilley.