London Underground workers are to stage a series of strikes next month in a dispute over pay and conditions, the RMT union has announced.The union will carry out rolling strike action across the Tube network for seven days beginning on Friday, September 5.In a statement, the RMT said “The strikes comes after management refused to engage seriously with union demands on pay, fatigue management, extreme shift patterns and a reduction in the working week, as well as failing to honour previous agreements made with staff.