Acknowledgements I am indebted to my publisher Samantha Jackson for asking me to write this book and helping me to design and refine the content and structure. Thanks to Martina O'Sullivan for editing this second edition. Thanks also to Richard Stagg of Pearson Education for his insightful suggestions on the content. I am very grateful to the rest of the Pearson team for their great professionalism. I was greatly helped by the wonderful input I got from my test readers: Chris Cant, Neil Hepworth, Barry Horne and Kay Hughes.