The Northern Line Night Tube is reportedly set to launch on Friday 18 November.
A BBC journalist tweeted that Tube staff have been informed of the start date.
NEW: Tube staff have been told Northern line night tube will start Friday 18th November. Nothing official yet.— Tom Edwards (@BBCTomEdwards) September 26, 2016
However, a spokesperson for Transport for London said the launch date for both the Northern Line and Piccadilly Line Night Tube services had not yet been confirmed.
The Victoria and Central Lines were the first to offer 24-hour services on Fridays and Saturdays, which launched in August after a long and protracted process which saw Tube workers embark on several strikes and the start date for the project pushed back on more than one occasion.
The next line to start running trains all night at weekends will be the Jubilee Line, which will begin its Night Tube service next Friday, 7 October.