Detectives in Greenwich investigating a serious assault near the O2 Arena have released the image of a possible witness.
The incident was Sunday, February 12 in Peninsula Square, SE10 at approximately 03:25am.
Police were called to reports of a disturbance and a 26-year-old man was found unconscious.
He was taken to hospital where he remains in a serious but stable condition.
The woman in the CCTV immediately came to the aid of the victim when he fell to the ground.
It is believed she would have had an unobstructed view of what had happened.
Police are asking this woman, any other witnesses or anyone with information to call Greenwich police on 101 or via Twitter @MetCC.
To give information anonymously contact Crimestoppers on 0800 555 111 or crimestoppers-uk.org
Two men have been charged in connection with the investigation and are due to appear in court later this month. A third man has been bailed pending further enquiries.