Why was Windsor town blocked?

Windsor town center was blocked as hundreds of young people skirmished with police who earlier had broken up a pop music festival in Windsor Great Park. Police said last night that 220 people had been arrested during the day, most of them in the park during the eviction operation. Thirty-six people were injured, 21 of them police officers. A woman police officer had a broken arm and one policeman was in Wexham Park Hospital, near Windsor, with chest injuries. Most of those arrested are accused of drug offences or of obstruction.