GCHQ, or Government Communications Headquarters, is the UK's intelligence and security organisation responsible for monitoring and analyzing electronic communications. Established in 1919, their primary focus is on signals intelligence (SIGINT), including intercepting and decrypting communication to gather information for national security and defense.

Every Christmas, GCHQ set a fun puzzle for secondary school students to have a go at and this year's is the trickiest yet!  The activity features seven complex puzzles, masterminded by GCHQ's top in-house puzzlers, testing a range of problem-solving skills and encouraging the use of teamwork to reveal the final festive message.

So why not test the code-breaking skills of your friends and family this holiday and become GCHQ super sleuths! Clink on the image above to reveal the puzzle.