How a Single Bakery Fire Burned Down Half of London: It Wasn’t Just the Flames—A 17th-Century Design Fueled the Disaster

In the early hours of September 2, 1666, a fire broke out in a bakery on Pudding Lane in London. What began as a seemingly minor incident quickly escalated into one of the most devastating urban fires in history. Within days, the blaze had consumed large parts of the City of London, destroying approximately 13,200 homes, 87 churches, and iconic structures such as Old St Paul’s Cathedral, the Royal Exchange, and the Guildhall. According to the London Museum, about four-fifths of the city was destroyed, leaving around 100,000 people homeless.

How could a fire starting in a single bakery grow so catastrophically? The causes were multifaceted. A dry summer, strong winds, tightly packed timber-framed buildings, flammable materials stored in warehouses (such as tar, rope, oil, and brandy), and the absence of a modern firefighting system all contributed to the rapid spread. However, one architectural feature common in 17th-century London played a crucial role: jettied houses.

Jettied houses were built with upper floors projecting outward over the street, sometimes so much that adjacent buildings on opposite sides nearly touched at higher levels. This design, intended to maximize living space in narrow streets, drastically reduced the gap between rooftops. As a result, fire did not need to cross the entire street—it could climb up the wooden walls and eaves of one building and leap directly to the upper floors of the neighboring structure. Streets, which should have acted as firebreaks, became pathways for flames.

The summer of 1666 had been exceptionally dry, leaving wooden structures as combustible as kindling. Strong winds carried embers far ahead of the main fire, igniting new blazes. Firefighting methods at the time were rudimentary: buckets, hooks, and 'fire squirts'—primitive hand pumps. The most effective tactic was to demolish buildings ahead of the fire to create firebreaks. However, London’s mayor, Thomas Bludworth, initially underestimated the threat and delayed large-scale demolitions. By the time authorities began tearing down buildings—sometimes using gunpowder—it was too late.

Even stone buildings were not safe. Old St Paul’s Cathedral, though made of stone, was undergoing repairs with wooden scaffolding. Surrounded by booksellers and printing shops, its interior was filled with highly flammable paper and books. On September 4, the fire reached the cathedral, and it was completely destroyed.

Official records list fewer than ten deaths, but this number is likely inaccurate. 17th-century record-keeping was incomplete, especially for the poor and those whose bodies were incinerated beyond recognition.

The fire led to sweeping reforms. In 1667, new building regulations were passed, banning jettied timber constructions and mandating brick or stone for all new buildings. The disaster reshaped London’s urban landscape and laid the foundation for modern fire-safe city planning.