Well this is familiar. No sooner has a start date for night tube been announced, than tube staff vote to go on strike.
Yesterday's announcement by Sadiq Khan that the Central and Victoria lines would be the first to open 24 hours at weekends was followed today by the RMT union saying that maintenance and engineering staff have voted "overwhelmingly" to walk out. 85% of those who voted backed the action, in a dispute over pay and pensions.
RMT General Secretary, Mick Cash said: "RMT members have now shown their anger at the way that tube lines have attempted to tie in attacks on pensions with the offer on pay and night tube.
"There are also major unresolved issues over the tube lines staffing arrangements for the night tube and over performance related pay.
"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."
Implementation of the night tube has suffered a series of set-backs. Former mayor Boris Johnson announced intentions for the night tube in September 2014, and planned for it to start a year later. But disputes with unions over pay, staffing and working conditions delayed the start.