The Night Tube finally begins this weekend, with London mayor Sadiq Khan expressing his surprise at the delay in the scheme.

Trains will operate through the night on the Victoria line and parts of the Central line, with the Jubilee, Northern and Piccadilly lines following in the autumn.

Mr Khan's predecessor, Boris Johnson, announced in September 2014 that the service would begin on September 12 2015, with Transport for London (TfL) promoting the benefits at last year's Rugby World Cup.

But a bitter dispute with the rail unions delayed the project and Mr Johnson was criticised for setting a start date before the issues were resolved.

Mr Khan said Mr Johnson, now Foreign Secretary, "gave up" on the all-night Tube before leaving City Hall in May.

He said: "It's not me making a cheap point, but the previous mayor did announce the Night Tube start date on one occasion and that wasn't met, on a second occasion, that wasn't met, on a third occasion, that wasn't met, and then gave up.

"My point is TfL staff work incredibly hard. It can't be beyond the wit of a full-time mayor and TfL to make this work properly.

"When I see the enthusiasm from employers in London, investors to London, tourists in London, about the Night Tube, it's surprising it's taken us this long to get it.

"I'm pleased and proud that we're here."

The mayor said he had ensured the introduction of all-night services was "meticulously" planned, with just two lines being initially opened because "we don't want a big bang with errors and mistakes".

He added: "There may well be teething problems when we first begin but the key thing is to learn from that and to improve upon that before we unveil the other lines later on this year."

Asked who would use the Night Tube, Mr Khan said passengers would include nurses, security guards, tourists and even "a middle-aged clubber like me coming home after a late night out with your missus".

He has recorded welcome messages which will be played over the public address system at Oxford Circus, which will be the busiest Night Tube station.