by Lamiat Sabin and Luke James

LONDON’S long-disputed Night Tube will be launched months after Tory leadership hopeful Boris Johnson has exited City Hall, the Morning Star can reveal.

Train drivers’ union Aslef told the Star that the weekend service is set to be rolled-out line by line from August after the London mayoral election in May.

The news pulls the rug out from under Mr Johnson, who had hoped to stage a media-schmoozing “big reveal” tomorrow with Transport for London (TfL) managing director Mike Brown at Ashford depot.

It also undermines his attempt to steal a march on fellow Tory leadership rival Chancellor George Osborne — who is set to announce more unpopular cuts on Wednesday.

To rub salt in the wound, the Night Tube is likely to open under a Labour mayor, as January polls gave Sadiq Khan a 10-point lead over Tory candidate Zac Goldsmith.

This would be a blow to Mr Johnson’s City Hall, which has pushed hard to get out the Night Tube announcement before elections to secure a “legacy” for the ruthless politician as he sets his sights on high office.

And last night he faced heavy criticism over his seeming use of key London infrastructure for petty political brinkmanship. A spokesperson for Labour mayoral candidate Sadiq Khan said: “Londoners want the Night Tube up and running as soon as possible — but it’s a shame Boris seems to be using this announcement to try to steal a march on George Osborne in the battle for the Tory leadership. Londoners deserve better.”

Over the course of his eight-year tenure as Mayor, Johnson has repeatedly picked fights with London Underground (LU) staff also represented by RMT, Unite and TSSA.

After announcing the Night Tube in September 2014 without taling to workers, 18 “torturous” months of negotiations followed, according to Aslef, over pay, rotas and concerns over passenger safety.

Trains will now run throughout the early hours on Fridays and Saturdays on the Victoria and Jubilee lines from August. The Central, Northern and Piccadilly line services will follow in September.

Plans for the all-night service are now being drawn up by Transport for London (TfL) after Aslef agreed to new part-time drivers being trained, which it said has led to a surge in membership.

At least 200 new part-time drivers will be needed to meet demand for the Night Tube, the union added.

Aslef LU organiser Finn Brennan said: “The new drivers can see what having a strong trade union means for protecting pay and working conditions and whole groups have been joining up together.

“The package the union has negotiated means they are guaranteed the same benefits as existing drivers and will be able to move to full-time roles if they choose to.”

TfL could have introduced the Night Tube earlier, the union added, but it took nearly two years for LU to agree to a contract that would benefit workers and passengers.