These brain-teasing puzzles and riddles will give you a taste of what it feels like to be tested by the keenest minds in the country.
Accompanied by nuggets of historical info such as the story of David Omand who was asked to translate an essay written in made-up Elvish and ended up as Director of GCHQ, or Jean Valentine, who volunteered in Dundee aged 18, disclosed that she loved the challenge of a cryptic crossword and found herself whisked down to Bletchley.
