In 1932 there suddenly appeared on the London streets a revolutionary new design with a full front and seats in the position where orthodox passenger vehicles had engines. An entirely new design of chassis was evolved by AEC at Southall, with the engine positioned on the offside frame member behind the front axle. After the success of the single deck Q with L.G.O.C and provincial operators, the L.P.T.B ordered 102 4Q4 type for Country Area bus work which entered service throughout 1935. Although far ahead if its time, the Q Type was only in production for 4 years but it paved the way for the underfloor engined type so much in evidence today. In August 1952, Q75 was withdrawn from normal passenger work and converted for use by the service fleet as a training vehicle for Civil Defence exercises, in which capacity it was converted into a mobile gas unit. It was renumbered in May 1954 to Q1035CD.