This is a biographical book. He was the H. O. Wills Professor of Physics and Head of Department, from 1981 to 1994. He was Deputy-Adjoint of the Institut Laue–Langevin from 1965 to 1988. He was elected a Fellow of the Royal Society in 1985 and was Physical Secretary and Vice President of the society from 1999 to 2004. He was President of the Institute of Physics from 2004 to 2006. Sir John's contributions have been recognised by the award of a CBE in 1997 and a Knighthood for services to Science and Technology in 2004.