I struggled to find information about the stocks in Berwick. I would imagine the stocks were used during Medieval and Renaissance times to publically punish and immobilise victims where there was an opportunity for passers-by to mock and ridicule and also throw things at them. These were near the town hall and the butter market and I would imagine then this was Berwick's central meeting point.
These earthworks provided extra security for the town. Now they offer a chance to get a little exercise, some nice views of the town and the North Sea and a chance to meet and speak with the locals.