The BBC reports:
A new video released by demonstrators shows a police officer beating a man in the head with a riot shield at the London G20 protest earlier this month.
The man is barged with a shield on the side of his head in the footage, shown on the Sunday Times website.
The video is embedded below.
At 4.50mins in to this clip an officer is clearly seen smacking a protestor across the head with his shield. At 7.49mins in an officer punches a protestor in the face.