A part of south west London's history is being demolished to make way for thousands of new homes.
Earls Court, the exhibition centre, is being knocked down. Kensington and Chelsea's planning committee approved the scheme last night.
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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.
Hay fever is an allergic reaction to airbourne pollen. There are 2 million sufferers in London (that's one in 5 people).