I always loved the busses the Leyland was in many ways as good as the Route master. The 73 remained a back loader after most of the fleet had become Atlantean. The Atlantean became the one man bus but originally it had conductors. Every now and then Leyland sent the Corpy new or experimental busses that?s why you see oddities around. The standard Atlantean became the norm for the corporation. Middle doors being the main change.