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.
Dennis Dragon
Between 1994 and 1998, Citybus introduced 80 12m Dennis Dragons and 40 10.3m Dennis Dragons. In 2000, Citybus rebuilt a 10.3 m Dragon (fleet number 701) as the world's first 3-axle double-decker air-conditioned trolleybus.