Consultants and MPs opposed to plans to close Lewisham's Accident and Emergency department have handed letters and a 20,000-signature petition to Downing Street.
Protesters, including Lewisham East MP Heidi Alexander, say the closure would leave them with one accident department for 750,000 residents.
The planned closure is part of a reorganisation aimed at saving the South London Healthcare Trust after it went into administration.
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Before the final declaration on Friday, the Conservative candidate looked set to lose the City Hall race to Labour's Sadiq Khan.
The Tooting MP has been the frontrunner in the counting process ahead of Tory challenger Zac Goldsmith.
It's not just London where elections have been taking place today. There were council elections taking place across the home counties.