Reuters is reporting that the RMT has voted in favour of strike action by a 6-1 margin.
No date has been set yet but it's understood that a walkout will be coordinated alongside Aslef.
Bob Crow is giving a press conference as we type this so we'll update this post with more details later this afternoon.
Update: 3,500 drivers across the Rail Maritime and Transport (RMT) union and Aslef will stage a 24-hour walkout on Tuesday 21 February and Thursday 2 March.
Aslef voted by 4-1 in favour of industrial action over a "serious breakdown" in relations with the company.
The good news is that Aslef Gneral Secretary Keith Norman has said that "considerable progress" had been made already during talks between the two sides:
During the past 10 days we have had constructive talks and have made considerable progress.
Because of that progress and the goodwill shown on both sides the Executive has resolved to postpone any industrial action for three weeks.