Former British Prime Minister Margaret Thatcher, who passed away earlier today, was in power for 11 and a half years, the "longer than any other British politician in the 20th century." However, her reign of power ended months after introducing a deeply unpopular—and, as critics stated, unfair—poll tax that plunged Great Britain into protests and riots.

The poll tax, known as Community Charge, had changed the old tax system by implementing a tax on each person (before, a tax was based on properties people owned or rented). However, there were problems—some renters could dodge payment and many of the wealthy ended up saving money, while the poor got hit hard. The Independent: "In practice, critics pointed out, that meant a millionaire living alone in a mansion would pay less than the average family."

Protests broke out all over the country, most notably in London on March 31st, 1990 in what's known as the "Battle of Trafalgar," with anti-tax protesters throwing rocks, bottles and stones at police officers.

From the NY Times on April 28, 1990:

Speculation that the tax would change was heightened after a report in The Economist in which the magazine quoted senior members of the Government as saying that at a private meeting Mrs. Thatcher ''agreed that the poll tax was unfair'' and that ''she cited, as an example, the amount she herself would have to pay and the saving she would make.''

Naturally, Thatcher's spokeperson denied she said that. But, as a BBC retrospective on the poll tax riots states, "By the end of the year, Prime Minister Margaret Thatcher had been forced to step down. She was replaced by John Major who scrapped the charge in favour of the council tax that continues today."