Andrew, thank you for everything. As a PhD supervisor you showed me how a scientist should be, gave me the opportunity to taste the thrill of discovery, and the latitude to explore ideas. Then and in the subsequent years, you were always there to provide wise advice, encouragement and inspiration. Your untiring support means so much to me and always will. It is an honour to have known you and to have worked with you. You were a one-off and cannot be replaced.