Under-fire health chiefs in north London claim their plan to close wards, axe jobs and sell buildings could be a template for a new kind of district general hospital.
Bosses at the Whittington in Archway want to put more emphasis on treating patients at home.
They plan to raise £17m by selling half of the hospital site to property developers. The number of births at the hospital would be capped at 4,000 a year. The workforce would be cut by 570.
The plan has attracted widespread local opposition.
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Paramedics were on standby outside the police cordon as armed officers stood by the property.
A team of researchers has taken samples from the ten busiest London Underground lines to work out which are the dirtiest.
The action comes on top of an emergency timetable which has seen hundreds of trains a day being axed.