Patrick O'Neill is the author of five previous edition of Cellarmanship, all published by CAMRA. He studied physics and spent more than 30 years working as an engineer in the electronics industry. His science and engineering experience proved useful in running CAMRA beer festivals and for several decades the bar and cellar of a busy Private Members' Club, and this book was produced as a result of that experience. The technical aspects of making, keeping and selling beer have always been of consuming interest to him.