RMT general secretary Bob Crow said:
"The outcome of these separate ballots will now be considered by RMT's executive but the message could not be clearer - we are stepping up the fight to protect agreements, jobs and working conditions across the whole of London and to eliminate the scourge of poverty pay on cleaning contracts."
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Former home secretary Sajid Javid revoked her British citizenship, a decision her lawyers argue was unlawful as it rendered her stateless.
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