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.
Red Arrow (bus)
London Transport had instigated a Bus Reshaping Plan in 1966 to examine bus service operation, and settled on replacing some double-decker buses with long single-decker buses, which would have extra capacity by implementing a 'standee bus' model as used on the continent, whereby the fixed seating in the bus would be minimised to that required off-peak, with hand holds fitted to allow maximum standee capacity at peak times. These buses would also have dual doors.