In 1932 there suddenly appeared on the London streets, a revolutionary new design with a full 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 sucess of the single deck Q with L.G.O.C and provisional operators, the L.P.T.B ordered 102 4Q4 for country area bus work, which entered service throughout 1935.Although far ahead of its time, the Q Type was only in production for 4 years but it proved the way for underfloor engined type so much in evidence today.