We were colleagues at Ruston and Hornsby, English Electric, Ruston Gas Turbines and finally Siemens. We first met at the Ruston and Hornsby Research Centre on Beevor Street in Lincoln. I was transferred from a Craft to a Technician Apprenticeship and joined the Instrumentation department at the Research and Development Centre. Derek was a fully fledged development engineer working on the company's latest product the AO. He looked after the 12AO as its Development Engineer. It was the only 'V' form configured development engine. When development and production of large diesel engines including the AO moved from Lincoln to Newton-le-Willows in Lancashire, those that weren't required for continuity of development and production were transferred to the fledgling Gas Turbine business of Ruston Gas Turbines. Derek was a senior engineer in the Mechanical Applications group. After a period writing manuals, I joined the controls Applications Group. The groups Mechanical applications, Electrical Applications and Controls Applications worked closely with each other to produce working packages to meet customers expectations. The company embarked on a computer based option selection system to aid production and speed up the Tendering process. Derek's product knowledge was second to none and he produced Product Definition books that contained the detailed product data for each of the different sizes of Gas Turbines (these books were produced in hard backed form). My next involvement with Derek was when my boss Pete Bonham and my colleague Andy Kelly left. I was assigned to work for Derek, to continue updating the option selection databases. I enjoyed working for Derek. He was generous with his time and from time to time we discussed our time on the AO diesel engine. I have great memories of my time working with Derek and working for him. He was a great engineer. Thank you Derek. Yours sincerely Ray Brumby