I witnessed the driver of the white Mini at the Inch roundabout, beside VW, slow down as they were exiting the roundabout & slam the brakes on, in an attempt to get the vehicle behind to rear end. After coming to a short stop, the driver in the Mini started blaring the horn & making hand gestures that were far from appropriate. The 2 vehicles had came onto the roundabout at different points also, which indicates no previous event that would cause road rage.