Power workers on London Underground are threatening eight days of strikes in a long-running row over conditions. Members of three trade unions are set to walk out from 8pm next Tuesday until 8pm on Wednesday July 9.
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The ComRes survey for ITV News and LBC showed the Labour candidate increasing his overall lead over Conservative rival Zac Goldsmith.
The latest poll for ITV London and LBC shows Sadiq Khan leads Zac Goldsmith by 45% to 36% on first preference votes.
Corbyn was unveiling a poster less than a mile away as Khan gave his final campaign speech to party supporters in London.