Unstable guy on Turnpike Lane this afternoon

Just a note to be careful around Turnpike Lane area.  I saw a man walking along the road this afternoon (towards Wightman Road junction, south side of the road) seemingly threatening or intimidating anyone unfortunate to be on his path with violent gestures.  I was on the other side of the road.  He walked up behind a local trader on the street who was wheeling a trolley and put his fingers to the back of the trader's head in the shape of a gun and said something to him, almost as if he was frog marching him at gunpoint.  Then further down the road he made out as if to headbutt two other pedestrians (separate incidents) - luckily both managed to move out of the way.  All three people looked pretty shaken and also bewildered as in all cases it was completely unprovoked.  Probably someone who is unstable but if you spot him best to get out of the way asap.  He was black, well over 6ft tall, short curly hair and was wearing a light coloured jacket, either gold or light green