

An extension to the Oxford Street area was excluded due to severe congestion there. One of the two routes, awarded to Stagecoach London, was for services between Trafalgar Square and Tower Hill, covering the most touristy section of route 15 taking in the Tower of London, Monument, St Paul's Cathedral and Trafalgar Square.

Only one route, 15H remained after the withdrawal of 9H on 25 July 2014, but the 15H route itself was withdrawn on 14 November 2020.

For Transport for London, they aimed to comply earlier with the last buses withdrawn in June 2008 with two exemptions - heritage routes. This route and route 9H were announced initially as 'A' and 'B' as short workings on existing routes to avoid any potential complications as Government's legislation requires buses to be fully wheelchair-accessible by 1 January 2017 in the entire United Kingdom. It was a short working of the standard route 15. It ran between Tower Hill and Trafalgar Square and was operated by Stagecoach London. London Buses route 15H was a Transport for London contracted bus route in London, England.
