On 31 August 1957 Dennis was at the Edinburgh Festival playing a concert in the Usher Hall. The Philharmonia Orchestra were playing Tchaikovsky Symphony No. 6, "Pathétique" with the conductor Eugene Ormandy. Unusually that day he seemed tired and Ormandy told him he should get more rest. But Dennis had a recording session the next morning in London, so after the concert he got into his car (his TR2), put his horn on the back seat and set off on the 380-mile journey back home.