Four calling birds, three french hens, two turtle doves and a cryptographic grid-shading brainteaser.
It may not have the same ring to it, but eavesdropping agency GCHQ has nevertheless stuck an infuriatingly complex puzzle in its official Christmas card this year, inviting participants to crack the complex code and reply with their answers.
Those who have time to pull themselves away from basting the turkey can attempt to complete the puzzle with a black pen to eventually reveal an image. Once the first puzzle has been completed it will lead to a series of increasingly complex challenges, the highly-secretive body has explained.
“This year, along with his traditional Christmas cards, director GCHQ Robert Hannigan is including a brain-teasing puzzle that seems certain to exercise the grey matter of participants over the holiday season,” a statement on the GCHQ website said.
Players, who are invited to make a donation to the National Society for the Prevention of Cruelty to Children, are invited to submit their answers via a given GCHQ email address by 31 January.
Designed by crypt analysts in GCHQ, the puzzle, which has been sent out to card recipients, is also available for members of the public to try out via GCHQ’s website.
Explaining the rules, GCHQ says: “In this type of grid-shading puzzle, each square is either black or white. Some of the black squares have already been filled in for you.
“Each row or column is labelled with a string of numbers. The numbers indicate the length of all consecutive runs of black squares, and are displayed in the order that the runs appear in that line. For example, a label “2 1 6” indicates sets of two, one and six black squares, each of which will have at least one white square separating them.”
