The GMB union says it expects between five and ten thousand people to join a march through west London today in protest against the closure of emergency departments at several hospitals.
Plans have been outlined for the closure of facilities at Charing Cross and Hammersmith & Fulham Hospitals, and Ealing and Central Middlesex Hospitals.
The Union says the closures would lead to longer waiting times at other hospitals.
A spokesperson for NHS North west London said the plan was currently being consulted upon, and they would like to hear people's views.
The march will start in Shepherd's Bush at midday.
More top news
The two newborn Sumatran tigers who are yet to open their eyes were born at London Zoo on Monday.
Boris Johnson has ruled himself out of a bid for the Tory leadership.
The man allegedly began 'injuring himself' with a payphone after he was placed in a cell.