Protesters have moved in on Battersea Park Adventure Playground this morning, in a bid to stop a planned demolition tomorrow.
local campaigners, Wandsworth Against Cuts, and Occupy London supporters are angry about the closure.
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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).