A study in puzzles you can do and puzzles you can't.

String, scissors, paper and pencil will be useful if you want to join in - but you can just sit back and feel superior as Ian McNaught-Davis tries out his favourite puzzles on a group of children. Mac, best known on TV for climbing the Old Man of Hoy and the Eiffel Tower, has been passionately keen on puzzles for the last 30 years. The children were intrigued by his selection of puzzles and games - they argued, sweated away, cracked some of them and got frustrated by others.