Production of mechanical components was undertaken chiefly at AEC's Southall site (though a significant number had Leyland engines) with body construction and final assembly at Park Royal Vehicles.

Although regulations already permitted 2-axle double deck buses up to 30 feet (9.14 metres) in length by the time the Routemaster went into full production, the majority of production examples were 27 feet 6 inches (8.38 metres) long, the introduction of 29 feet 11 inches (9.12 metres) "long" types being delayed by union resistance to the extra work for conductors.
Production of mechanical components was undertaken chiefly at AEC's Southall site (though a significant number had Leyland engines) with body construction and final assembly at Park Royal Vehicles.
Although regulations already permitted 2-axle double deck buses up to 30 feet (9.14 metres) in length by the time the Routemaster went into full production, the majority of production examples were 27 feet 6 inches (8.38 metres) long, the introduction of 29 feet 11 inches (9.12 metres) "long" types being delayed by union resistance to the extra work for conductors.
AEC Routemaster