But speaking during the recording of a mayoral debate for ITV's London Tonight, to be screened this evening, he ruled out a no-strike agreement urged by his critics. "The reality is the RMT are not going to sign up to a no-strike agreement and I don't have the legal power to impose one," he said. "It's difficult when there is a culture of industrial action, and being at loggerheads with management, to break that. We weren't going to break that in one year but I do think we will break it." The stoppage is timed to last for 24 hours from 9pm on Wednesday. But services will stop running or stations will be closed earlier and will stay shut through Thursday.