Double-decker bus
The first commercial horse-drawn double-decker omnibuses were introduced in England in 1847 by Adams & Co. of Fairfield, Bow, then improved upon by John Greenwood, who introduced a new double-decker in 1852.
History of bus transport in Hong Kong
In 2010, franchised bus operators introduced the first two-axle air-conditioned double deckers. KMB introduced one Alexander Dennis Enviro400, Citybus introduced two Enviro400s, later in the same year both KMB and Citybus have received one two-axle Volvo B9TL. The first production two-axle air-conditioned double deckers appeared in 2011.