Charles Dickens is best known for his sagas of poverty and beauty in London—stories that contain slice-of-life details only a man who had lived in such conditions could capture. But Dickens did more than raise awareness of the plight of the poor in England. More than once, his writing and publishing actually influenced public policy—like the time he helped Britain repeal a 156-year-old tax on windows.

It may seem incredible today, but in Dickens’s time people had to pay for the privilege of having light and air in their homes, thanks to a law designed to turn England’s buildings into revenue streams. Between 1696 and 1851, Britain’s Parliament put a premium on windows, shaping the architecture of the day and even endangering lives.

The window tax was just one of scores of creative taxes designed to raise money for the government by making people pay even more for the places in which they lived. Introduced in 1696 in an effort to raise money to offset the costs of creating new currency—and to pay for the Crown’s exorbitant expenditures on wars, diplomacy and lavish palaces—the duty was designed to tax richer people more and poorer individuals less, based on the assumption that people with more money could afford more windows.

However, this wasn’t always the case. In cities, poor people lived in crowded tenement buildings with lots of windows. A provision of the law put the tax burden for those buildings on landlords in an attempt to help the poor. But that had a surprising effect. Instead of just paying the tax, people with a lot of windows—including urban landlords—started blocking out apertures with bricks or wood. They also raised rents on tenants to recoup the costs. And when they built new buildings, they often reduced the number of windows—or even eliminated them—to avoid the tax.

As a result, life in tenements became not just uncomfortable, but unhealthy as well. Epidemics spread quickly in unventilated spaces, and poor people suffered in buildings with little natural light.

The taxes were not the only ones that had the unintended effect of turning necessities into luxuries. Take the hearth tax, also known as the chimney tax: Between 1662 and 1689, this duty required people to pay money for every stove or fireplace in their dwelling. At first, the tax was levied on every Englander without exception, but the labyrinthine laws were continually being changed, and Parliament eventually allowed exemptions for poor people. Regardless, the tax encouraged people to crowd into smaller dwellings, use unsafe heating methods or go without a fire altogether to avoid the levies. Even things like candles, salt and soap were taxed by Parliament at various points in history.

All of these taxes were unpopular, especially since they usually punished a building’s occupants—rather than its owner—for the “luxuries” of things like heat and light. But the window tax was the longest lasting and the most hated. Sometimes, tax rates rose in response to current events, as when Prime Minister William Pitt tripled the tax to pay for the Napoleonic Wars in 1797 and to make up for lowered taxes on things like tea. Such inconsistencies even added to the English resentment of the Irish, who were exempted from the window tax because of the island’s extreme poverty.

No one was more aware of the plight of England’s poor than Dickens. When he was 12 years old, in 1824, his father was imprisoned because of his inability to pay his debt. Charles was sent to live with a family friend and forced to leave school. Instead of pursuing an education, the young Dickens worked ten-hour days in a filthy factory, pasting labels on bottles of shoe polish.

This experience shaped the rest of Dickens’s life. Barred by class and finances from attending a university, he educated himself, then became a journalist covering Parliament. But he never stopped thinking about—or writing about—England’s poor. He covered them as an investigative journalist and later, as a novelist, writing sympathetic stories of their worries and exposing the dangerous conditions in which they lived.

As Dickens’s serial novels—The Pickwick Papers, Oliver Twist, and others—became more and more popular, his influence grew. He started his own magazine, Household Words, and used it as a vehicle for his political and social opinions.

About a month before the magazine’s release in 1850, Dickens’s friend Charles Knight wrote a letter asking if he’d consider publicly protesting another tax—one on paper. “I quite agree with you,”Dickens responded. “But when I think of the condition of the great mass of the people, I fear that I could hardly find the heart to press for justice in this respect, before the window duty is removed. They cannot read without light. They cannot have an average chance of life and health without it.”

Knight’s request seems to have prompted Dickens to act. Just months after the first edition of the magazine was published, he printed a fiery piece on the window tax called “Health by Act of Parliament.” Written by his co-editor William Henry Wills, it argued that the true victims of the window tax were the most forgotten. “When a poor man or woman in a dark, close, smoky house is laid up with scrofula, consumption, water in the head, wasting, or a complication of epidemic diseases,” Wills wrote, “nobody thinks of attributing the illness to the right cause;—which may be a want of light or air.”

A few months later, Dickens inserted himself into the fray. He asked a friend for more information on the “absurdities and evils” of the tax, then wrote a rousing indictment called “Red Tape.” The humorous piece pokes fun at England’s endless bureaucracy, but it also contained a plea to protect the poor. “A most unnatural percentage of them,” Dickens wrote in the piece, were “consumptive, and always sliding downward into Pauperism” due, in part, to the tax. Dickens—then one of the most popular and influential voices in England—also spoke publicly against the tax.

It worked. Later that year, 1851, the tax was repealed after 156 years in effect. Today, you can still glimpse the legacy of the tax in the blocked-out windows of historic buildings across Britain—and in the big panes of glass, people bought to celebrate once the tax was finally lifted.