A petition with over 21,000 signatures opposing plans to close Lewisham's Accident and Emergency Department will be handed in to Downing Street later.
Protestors have demonstrated against the closure in recent weeks.
The MP for Lewisham East, Heidi Alexander, will join doctors and consultants to deliver the document and other letters.
More top news
A 24-year-old man has been arrested on suspicion of murder after the body washed up on the Thames shoreline.
Seven people have now been arrested after a man died from serious head injuries
The 38-year-old officer was on his way home from a night shift when he collapsed. His death is not being treated as suspicious.