I can only echo what has already been said. My condolences to his family. I lost my Dad recently and am still coming to terms with it. I know how hard it will be for them.
Rest in peace Derek. My condolences to all his family and friends. Along with many others I enjoyed his wealth of contributions to FM. It's sad news indeed.
Just to endorse everybody else's comments. It is always sad to lose someone of Derek's experience and ability. My thoughts go out to his friends and loved ones. RIP Derek. Pete.