The poll tax riots were a series of riots in British towns and cities during protests against the Community Charge (commonly known as the "poll tax"), 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. Background The advent of the poll tax was due to an effort to alter the way the tax system was used to fund local government in the UK. The system in place until this time was called "rates" and had been in place in some form from the beginning of the 17th century. The rates system has been described as "a levy on property, which in modern times saw each taxpayer paying a rate based on the estimated rental value of their home". The Thatcher government had long promised to replace domestic rates, which were unpopular, especially among Conservative voters. They were seen by many as an unfair way of raising revenue for local councils. It was levied on houses rather than people. The proposed replacement was a flat-rate per capita Community Charge—"a head tax that saw every adult pay a fixed rate amount set by their local authority". The new Charge was widely called a "poll tax" and was introduced in Scotland in 1989 and in England and Wales a year later. The Charge proved extremely unpopular; while students and the registered unemployed had to pay 20%, some large families occupying relatively small houses saw their charges go up considerably, and the tax was thus accused of saving the rich money and moving the expenses onto the poor. In November 1989 the All Britain Anti-Poll Tax Federation was set up by the Militant tendency. Other groups such as the 3D () network provided national coordination for anti-poll tax unions who were not aligned to particular political factions. After the leadership of the Labour Party refused to back any demonstration against the poll tax, the All Britain Federation called a demonstration in London for 31 March 1990, the day before the tax was due to be launched. During the early months of 1990, over 6,000 anti-poll tax actions were held nationwide, with demonstrations in cities around England and Wales drawing together thousands of protestors, in a wave of protests which attracted notably large numbers in the South West.