Brian Kalule, 38, was on escorted leave with a member of staff in the hospital grounds on the afternoon of Wednesday, 2 December when he ran away.
The last sighting of Brian is from CCTV from a shop in Shooters Hill at around 2.38pm that day. He has not been seen since and it is not known where he has gone.
He is not believed to be in contact with any family or friends.
Brian suffers with his mental health and also requires medication for a number of physical conditions.
If seen by any members of the public, he should not be approached. Instead, call 999 immediately.
Anyone who has information as to Brian’s whereabouts should call 101 ref CRIS 3627373/20.