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 1981, CMB and KMB introduced the first 12-metre 3-axle double-deckers (MCW Metrobus). Another three 12-metre 3-axle double-decker bus models were introduced in late 1981/early 1982, namely Volvo Ailsa B55, Dennis Dragon/Condor and Leyland Olympian, all except the Volvo Ailsa are second generation rear-engined double-deckers.