When she sat down in that Edinburgh café almost three years ago to write Harry Potter and the Philosopher’s Stone, J.K. Rowling apparently determined that it would take a further six books to tell the complete story of her pubescent wizard. Millions of entranced and thoroughly hooked readers around the world are now breathlessly awaiting volume four. The books are immensely readable with a strong narrative drive, and Rowling cleverly leaves major plot points unanswered; one has to get the next in the series or die of curiosity. The same technique has served John Marsden well. Pity the poor parent who back in 1993 all unknowingly bought Tomorrow, When the War Began and then saw a further six titles progressively hit the bookshops, all in hardback first release, and all extending the saga. Many readers, including this one, wish he had stopped at number three but the temptation to continue must have been huge.