In 1952 Den did his National Service with the Royal Air Force. He attended a 6 weeks training course as an RAF motorcyclist at RAF Debden, a former Battle of Britain airfield near Saffron Waldon in Essex which was home to the RAF Technical College. He was trained to ride all types of motorcycles used by the RAF, to carry out routine maintenance, and to do convoy duties and any other work for which motorcycles are required. In hi discharge papers Den is described as being 5'61/2" tall, with brown hair, grey eyes and as being of smart appearance with a fresh completion. His conduct, co-operation and abilities as a tradesman were described as being very good.