The Royal Marsden Hospital on Fulham Road, Chelsea is on fire.
A full evacuation is in progress. There are no reports yet of casualties or injuries; however, the blaze looks very serious.
According to the BBC, 'much of the roof has been destroyed'.
The hospital is a major treatment and research centre for cancer.
Ironically, a neighbouring headline on the BBC site asks 'Is the NHS working where you live?'.
We'll update the story with any further developments.