Presumption of guilt in disturbed areas shifts burden to accused when present during firearms or explosives use. A statutory presumption shifts the evidential burden where a person accused of specified violent public order offences is shown to have been present in a disturbed area or an area of prolonged extensive disturbance at a time when firearms or explosives were used from that place against forces maintaining public order, and, unless the contrary is shown, the person is presumed to have committed the offence.