Originally planned to be a three-year event awarded the Rudge-Whitworth Triennial Cup, with a winner being declared by the car which could go the farthest distance over three consecutive 24-hour races, this idea was abandoned in 1928 and overall winners were declared for each single year depending on who covered the farthest distance by the time 24 hours were up.
Orixinalmente planeado para ser un evento de tres anos, recibiu a Rudge Whitworth Trienal Cup, sendo declarado gañador o coche que percorrera a maior distancia ao longo de tres carreiras consecutivas de 24 horas, con todo, esta idea foi refugada en 1928 e os gañadores foron declarados cada ano en función de quen cubria a maior distancia en 24 horas.