Night Tube: When will the 24-hour London Underground start and which lines will run?

Londoners will be able to travel by tube throughout the night by the end of this summer, London Mayor Sadiq Khan has announced. After a year of delays and discussion over pay and conditions for London Underground staff, a date has finally been set to launch the Night Tube service in August.

"The night tube is absolutely vital to my plans to support and grow London's night-time economy – creating more jobs and opportunities for all Londoners. The constant delays under the previous mayor let Londoners down badly," Khan said.

"I have made getting the night tube up and running a priority, and London Underground has now confirmed that services on the first two lines will launch on 19 August."

When will the service begin?

The first night tube services will launch on the Central and Victoria lines on Friday 19 August, with services on the Jubilee, Northern and Piccadilly lines following in the autumn. The Night Tube will offer a 24-hour service on Friday and Saturdays.

"Across the Night Tube lines, you will be able to travel between Central London and the outskirts of the city. It will be pivotal to London's night economy and complement our existing Night Bus services and London Taxi and Private Hire vehicles," the Transport for London website states.

The service will run as follows:

Between Ealing Broadway and Loughton/Hainault on the Central line.

Across the entire of the Victoria and Jubilee lines, with trains running on average every 10 minutes.

Across the entire Northern line, except the Mill Hill East and Bank branches.

Across the Piccadilly line between Cockfosters and Heathrow Terminal 5. There will be no service on the Terminal 4 loop, or between Acton Town and Uxbridge.

Will the service expand?

Transport for London has said it has plans to extend the Night Tube service to parts of the Metropolitan, Circle, District and Hammersmith & City lines in the future. By 2017, services could also run on parts of the London Overground, with the Docklands Light Railway (DLR) following suit by 2021.

How was a deal reached?

Rows over staffing, pay and working conditions delayed the launch of the all-night service for more than a year. The dispute led to service-wide strikes as union members took industrial action.

The Rail, Maritime and Transport (RMT) union is still in dispute with London Underground over conditions for engineering and maintenance workers associated with the new service. A deal was reached for the union's drivers in March, but an industrial action ballot is being held for conditions for engineers.

RMT general secretary Mick Cash has said there are still "major" unresolved issues over safety and pensions.