London Buses route N15

From the Wikipedia page

London Buses route N15 is a Transport for London contracted bus route in London, England. Running between Romford and Trafalgar Square, it is operated by Stagecoach London.

This is a night service for route 5(Romford - East Ham) route 115(East Ham - Blackwall) and route 15 (Blackwell - Trafalgar Square)