In the 1950s route 27 became the main route and route 27A was withdrawn from being the main route. In 1950, the route took part in trials to reassure the police that eight-foot buses presented no danger to other traffic. The route operated from Holloway garage at the time.[4]
In March 2019 the section between Chiswick Business Park and Hammersmith Grove was withdrawn. The 24 hour service was also removed with route N27 being introduced to cover the night service.
Singer Matt Monro was a driver on route 27 prior to beginning his musical career.[13] In January 2011, bus driver Kenny MacKay published a book titled The Road Ahead: Observations of a London Bus Driver about his experiences as a driver on route 27.[14]