In the years immediately following World War II, bus operators in the United Kingdom faced a downturn in the numbers of passengers carried and manufacturers began looking at ways to economise. A few experimental rear-engined buses had been produced before the war but none successfully made it beyond the prototype stage. The need to minimise the intrusion of the engine into passenger carrying space was a priority, leading to several underfloor-engined single-deck designs. However, such designs raised the height of the floor of the vehicle, forcing additional steps at the entrance. On double decker buses, these problems were amplified, causing either an increase in the overall height of the vehicle or an inadequate interior height.