The Poll Tax Riots were a series of riots in British towns and cities during protests against the poll tax (officially known as the "Community Charge"), introduced by the Conservative government of Prime Minister Margaret Thatcher. The largest protest occurred in central London on Saturday, 31 March 1990, shortly before the tax was due to come into force in England and Wales. The disorder in London arose from a morning demonstration which became a violent confrontation between the Metropolitan Police Service (MPS), protesters and other activist demonstrators, which ended in rampaging and looting until 3 a.m.