Probably best to try this one before starting on the sherry (Picture: PA)

If you have any friends or family working at the UK’s spy agency GCHQ, you might be getting this puzzle in the post.

The festive brainteaser features on the organisation’s official Christmas card – but we recommend you try searching for the answers before starting on any Christmas chocolate liqueurs.

It has also beeen sent to schools, designed to test pupils’ problem solving skills, as well as knowledge of key subjects and ability to work as a team.

Those who crack all the puzzles will uncover a hidden festive message.

But the answer has not yet been released so as to not spoil the mystery. Hints will be posted on the official GCHQ social media channels throughout today, with people also invited to join in at home.

Director of Cheltenham-based GCHQ Sir Jeremy Fleming sent the card and puzzle to his contacts around the world.

A GCHQ spokesman said: ‘The puzzle, masterminded by a team of the agency’s in-house puzzlers, features on Director GCHQ’s Christmas card.

Get your thinking cap on (Picture: PA)

‘The card is sent to partners in the UK and around the world who work with the intelligence, cyber and security agency to counter threats, including hostile state activity, terror groups and organised crime gangs.

‘Secondary school classes across the country will need to work as a team to crack the Christmas challenge, featuring seven fiendish puzzles.

‘The puzzles are based on the seven disciplines of: languages, engineering, codebreaking, analysis, maths, coding and cyber security – all key skills needed at GCHQ to help keep the country safe.

‘But this year’s challenge comes with a twist, once they solve all seven puzzles, schoolchildren will need to think outside the box, using the design on the front of the card to assemble the answers, forming three separate What3Words locations.

‘Joining the three place names together will reveal the special festive answer.

‘Based on the seven disciplines featured in the recently published Puzzles For Spies book, the #GCHQChristmasChallenge tests the lateral thinking, ingenuity and perseverance needed by those working at GCHQ across its missions to keep the country safe.’

What3Words is a mobile phone app which divides the world into a grid of three metre squares and allocates three words to each square to enable people to share their precise location.

Sir Jeremy said: ‘From breaking Enigma to harnessing the latest cutting-edge technology, our brilliant people have worked together throughout our history to help keep the country safe.

‘This year’s GCHQ Christmas Card Challenge gives an insight into the skills we need every day as part of our mission – from languages to coding.

‘But skills alone won’t be enough to crack this one. Puzzlers need to combine a mix of minds to solve the seemingly impossible.’

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Those who crack all the puzzles will uncover a hidden festive message from GCHQ.