“Since the arrival, at the very end of 2004, of the number grid game sudoku, Britain – like Israel, France, India and the US – has become a puzzle nation. The statistics are amazing. Sudoku puzzles now feature in most national newspapers, and are moving on to mobile phones and pay-to-play websites. The magazine Puzzler Sudoku was first launched in March with a circulation of just 15,000. It now sells 300,000.”