A group of 140 senior doctors have written to David Cameron expressing concern over plans to close several accident and emergency units in west London.
In an open letter, the doctors said they have yet to see evidence that plans to centralise and downgrade A&E services are beneficial to patients.
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David Cameron said the Met proved it can "do more with less" and declined to criticise the Mayor of London for his water cannon spend.
A group of disabled activists threw toys and balls at him as he entered the conference.
A wet start to the week and the unsettled weather is set to continue over the next few days.