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GCHQ Release Cryptic Christmas Card Puzzle

GCHQ has released a head-scratching Christmas card to keep puzzle fans busy over the holidays.

Instead of the traditional Santa and reindeer, Britain's intelligence and security agency has designed a festive card featuring a cryptographic challenge.

Participants have to fill in a grid-shading puzzle to unveil a picture, which is the first in a series of increasingly complex challenges.

The competition will also raise funds for the NSPCC, with the winner to be announced after January 31 2016.

The puzzle's left us stumped.

The GCHQ website explains how to get started: “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.”