(Hey, it's as reasonable as any of the rest of this wild speculation here.)
You're thinking of the Great London Plague of 1664-1665, which is generally considered to have been halted by the London Fire of 1666 (though the number of infected and deaths had already begun a steep decline). The Black Death was in the 1340s.
"You're thinking of the Great London Plague of 1664-1665, which is generally considered to have been halted by the London Fire of 1666 (though the number of infected and deaths had already begun a steep decline). The Black Death was in the 1340s."
It was still bubonic plague. There were scattered, periodic outbreaks throughout 1340 - 1666.
I thought the thing about the great fire was that people built with brick instead of wood after that, and for some reason that helped with the rodent population.