The Guardian quick crossword is one of the most popular items in the paper, with tens of thousands of readers attempting to solve it every day. Challenging enough to tax the braincells, but designed so that it can be completed on the train or in a lunch hour, the puzzle has countless fans and has spawned many series of books. This is the sixth book in that series, and it includes 150 puzzles from the Guardian archive that are guaranteed to appeal to everyone from novices to experts.