Very sad news. I remember Derek with great affection from online encounters over Sibelius. I enjoyed conducting his Serenade in 11/4 with my brass band in Indiana many times: it never failed to please. Despite lacking technical expertise, in retirement from a distinguished teaching career he was tireless in fighting the vast array of technology he had to master to synthesize his music. His was a life lived to the full and touching many others who will not forget him. RIP.