The Great plague of London. London was visited by the plague for the last time in 1665, when 68,596 people are said to have died. In 1625, (another terrible year), 35,417 people died, (it is said about 5000 a-week); and in 1603 as many as 30,561. The Great Fire of London in 1666 (the year after the Great Plague) was the means of destroying so many low ill-drained alleys, and ill-ventilated houses, that we may safely attribute our after freedom from this dreadful scourge to the purification by fire of our old London purlieus.
Source: A Handbook for London, Past and Present. Peter Cunningham. Published by John Murray 1849.