Here's who came closest to solving GCHQ's 'fiendishly difficult' Christmas puzzle

Of the 30,000 people who made it to the final round of the complex task, none managed to get all of the answers correct

The GCHQ Christmas puzzle is not for the faint hearted (GCHQ)

Three men have been crowned winners of the annual GCHQ Christmas puzzle challenge, beating more than 600,000 people to the top spot.

Of the 30,000 people who made it to the final round of the complex task, none managed to get all of the answers correct.

However, Irish-born David MacBryan, 41, who now lives in Edinburgh, Wim Hulpia, 40, from Belgium, and American Kelley Kirklin, 54, who now resides in London, came closest.

Mr MacBryan, who considers himself a professional quizmaster, told the BBC: "The more puzzles you do, the better you get at doing puzzles - and I have done a lot of puzzles. I am a bit of an addict."

The puzzles, launched in early December, require a mixture of mathematics, linguistic and problem-solving skills and are painstakingly produced by a team at GCHQ over several months.

More than 600,000 people attempted the first stage of the brainteaser, of which over 30,000 advanced to the final stage

One of the puzzle making team, who wished to remain anonymous, told the BBC: "I don't think there's any coincidence that you find a bunch of people setting these sorts of problems who are also working on the kind of problems GCHQ works on.

"We are faced with problems where there is incomplete information, there is ambiguous information, you have to decide whether you have pushed an angle far enough… that's the sort of thing we expect people to do with these sort of questions."

The three winners will receive a GCHQ paperweight and a copy of Alan Turing biography Decoded, signed by his nephew Dermot Turing.

The answers are now available from the GCHQ website.