Tube engineering and maintenance workers belonging to the RMT union have voted to go on strike in a row linked to the new night Tube.
Union members are unhappy about pay, staffing and pension arrangements for workers employed by Tube Lines, the former PPP contractor bought out by London Underground.
According to the RMT, 85% of affected members backed a walk-out.
RMT general secretary Mick Cash said: “The ballot result will be considered by RMT’s executive and now that the members have shown their anger it is absolutely essential that there is the earliest possible resumption of serious and meaningful talks on these issues and the union is ready to engage in those talks.”
The result of the ballot comes just a day after London Mayor Sadiq Khan announced that the first all-night Tube services would start on August 19th.
During the build up to this month’s mayoral election Mr Khan criticised former mayor Boris Johnson for failing “to negotiate or even meet” with unions to resolve their grievances.
Asked whether Mr Khan would be meeting the union to discuss their complaint, a spokesperson for the Mayor said: “All of the working practices within London Underground that need to change to enable a Night Tube service to begin have been discussed and agreed with the unions.
“There is one outstanding issue that needs to be resolved and it does not affect the Central or Victoria Lines where Night Tube services will begin on 19 August.
“The outstanding issue regards access to the Transport for London pension scheme for Tube Lines maintenance staff working on the Jubilee, Northern and Piccadilly Lines. The Mayor’s team at Transport for London are doing their utmost to resolve the issue.”
