If you take part in a march on the planned route, for example, then there shouldn’t be any reason for concern.
If you stay aware of crowd and police movements during marches you can usually spot if there’s a police clampdown coming and choose to remove yourself from an area before the police form a dense ring around you. This is known as kettling.
We encourage people not to panic – even if you are kettled you are unlikely to be arrested.
Finally, note that almost all arrests at demonstration in the UK are for very minor offences – it is extremely rare to be arrested for something that could put you in prison.