Partly funded by The HELP (Helicopter Emergency Landing Pads) Appeal, a 25m by 25m helipad will enable seriously ill patients to be brought by air ambulance for treatment at the hospital's Major Trauma Centre.
A lift shaft in the middle of the wing is being built so that patients can be lowered quickly and smoothly into the hands of medical experts.
The helipad - which is due for completion in January 2014 - is being constructed by Miller Construction and will be the second hospital helipad in London and the first south of the river.
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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.