My only regret is that I shan't be alive to savour my retrospective triumph. But that is of small account. I savour it every day of my life. I shall have done the one thing I resolved to do when I was twelve years old - and the world will know it. In The Part Time Job, the extraordinary P.D. James - who would have been celebrating her 100th birthday this year - takes us inside the mind of a man who has patiently waited decades to enact his revenge on a school bully.