The Turing Tests Expert Sudoku: Eric Saunders

Designed to present a tough challenge, these puzzles are divided into three levels of difficulty, the final of which is for true experts.

This sudoku collection includes a foreword written by Sir Dermot Turing, nephew of Alan Turing and trustee of Bletchley Park, the former British codebreaking HQ where Alan Turing worked. Its retro 1940s cover is reminiscent of wartime book designs and makes a wonderful gift.

Set your mind to work and see whether you have the skills to become a Bletchley Park number cruncher.