The Great Plague of London, lasting from 1665 to 1666, was the most recent major epidemic of the bubonic plague to occur in England. It happened within the centuries-long Second Pandemic, a period of intermittent bubonic plague epidemics that originated in Central Asia in 1331 (the first year of the Black Death), and included related diseases such as pneumonic plague and septicemic plague, which lasted until 1750.
The Great Plague killed an estimated 100,000 people—almost a quarter of London's population—in 18 months. The plague was caused by the Yersinia pestis bacterium, which is usually transmitted to a human by the bite of a flea or louse.
The 1665–66 epidemic was on a much smaller scale than the earlier Black Death pandemic. It became known afterwards as the "great" plague mainly because it was the last widespread outbreak of bubonic plague in England during the 400-year Second Pandemic.
London in 1665
The plague was endemic in 17th-century London, as it was in other European cities at the time. The disease periodically erupted into massive epidemics. There were 30,000 deaths due to the plague in 1603, 35,000 in 1625, 10,000 in 1636, and smaller numbers in other years.
In late 1664, a bright comet was seen in the sky, and the people of London became fearful, wondering what evil event it portended. London at that time was a city of about 448 acres surrounded by a city wall that had originally been built to keep out raiding bands, and, in the south, by the River Thames. There were gates in the wall at Ludgate, Newgate, Aldersgate, Cripplegate, Moorgate, Bishopsgate and Aldgate, and the Thames was crossable at London Bridge. In the poorer parts of the city, filled with overcrowded tenements and garrets, hygiene was impossible to maintain. There was no sanitation, and open drains flowed along the centre of winding streets. The cobbles were slippery with animal droppings, rubbish and the slops thrown out of the houses; they were muddy and buzzing with flies in summer, and awash with sewage in winter. The City Corporation employed "rakers" to remove the worst of the filth, and it was transported to mounds outside the walls, where it accumulated and continued to decompose. The stench was overwhelming, and people walked around with handkerchiefs or nosegays pressed against their nostrils.
Some of the city's necessities, such as coal, arrived by barge, but most came by road. Carts, carriages, horses and pedestrians were crowded together, and the gateways in the wall formed bottlenecks through which it was difficult to progress. The nineteen-arch London Bridge was even more congested. Those who were better-off used hackney carriages and sedan chairs to get to their destinations without getting filthy. The poor walked, and might be drenched by water tossed up by wheeled vehicles, slops thrown into the street, or water pouring off overhanging roofs. Another hazard was the choking black smoke belching forth from soap factories, breweries, iron smelters and about 15,000 households that were burning coal to heat their homes.
Outside the city walls, shanty towns with wooden shacks and no sanitation had sprung up, providing homes for the craftsmen and tradespeople who had flocked to the already overcrowded city. The government had tried to limit the development of these "suburbs", but had failed: Over a quarter of a million people lived in them. When Royalists had fled the country during the Commonwealth, they had left many fine town houses vacant, and some immigrants to London had crowded into them, converting them into tenements that housed different families in every room. These properties were soon vandalised and became rat-infested.
The City of London proper was administered by the Lord Mayor, the Aldermen and the common councillors, but some parts of the greater metropolitan area were not legally part of the city. Some of these areas, both inside the City walls and outside its boundaries, had long been organised into districts of various sizes, called "liberties", that had historically been granted rights to self-government. (Many had originally been associated with the religious institutions that were abolished in the Dissolution of the Monasteries, whereupon their historic rights and property had been transferred to secular owners.)
By 1665, the walled City was surrounded by a ring of liberties which had come under its authority, and these had come to be referred to collectively as 'the City and Liberties'. However, this area was surrounded by additional suburbs with other independent administrations. For example, Westminster was an independent town with its own liberties, joined to London by urban development, and the Tower of London was an independent liberty. Areas that were not part of any of these various independent administrations came under the authority of the county of Middlesex if they were north of the river, and under the authority of Surrey if they were south of the river.
At that time, bubonic plague was a much feared disease, but its cause was not understood. Many mistakenly blamed emanations from the earth, "pestilential effluvia", unusual weather, sickness in livestock, abnormal behaviour of animals or an increase in the numbers of moles, frogs, mice or flies. It was not until 1894 that its causal agent, the bacterium Yersinia pestis, was identified by Alexandre Yersin, and its transmission by rat fleas became known. Although the Great Plague in London was long assumed to be bubonic plague, caused by Yersinia pestis, this was only confirmed (by DNA analysis) in 2016. It is now believed that human body lice also played a key role in causing infections, perhaps more so than rats.
The recording of deaths
In order to judge the severity of an epidemic, it is first necessary to know how big the population was in which it occurred. There was no official census of the population to provide this figure, and the best contemporary count comes from the work of John Graunt (1620–1674), who was one of the earliest Fellows of the Royal Society and one of the first demographers, bringing a scientific approach to the collection of statistics. In 1662, he estimated that 384,000 people lived in the City of London, the Liberties, Westminster and the out-parishes, based on figures in the Bills of Mortality published each week in the capital. These different districts with different administrations constituted the officially recognized extent of London as a whole. In 1665, he revised his estimate to "not above 460,000". Other contemporaries put the figure higher (the French Ambassador, for example, suggested 600,000), but with no mathematical basis to support their estimates. The next largest city in the kingdom was Norwich, with a population of 30,000.
There was no duty to report a death to anyone in authority. Instead, each parish appointed two or more "searchers of the dead", whose duty was to inspect a corpse and determine the cause of death. A searcher was entitled to charge a small fee from relatives for each death they reported, and so habitually the parish would appoint someone to the post who would otherwise be destitute and would be receiving support from the parish poor rate. Typically, this meant searchers would be old women who were illiterate, might know little about identifying diseases and who would be open to dishonesty. Searchers would typically learn about a death either from the local sexton who had been asked to dig a grave or from the tolling of a church bell. Anyone who did not report a death to their local church, such as Quakers, Anabaptists, other non-Anglican Christians or Jews, frequently did not get included in the official records. Searchers during times of plague were required to live apart from the community, avoid other people and carry a white stick to warn of their occupation when outdoors, and stay indoors except when performing their duties, to avoid spreading the diseases. Searchers reported to the Parish Clerk, who made a return each week to the Company of Parish Clerks in Brode Lane. Figures were then passed to the Lord Mayor and then to the Minister of State once plague became a matter of national concern. The reported figures were used to compile the Bills of Mortality, which listed total deaths in each parish and whether by the plague. The system of Searchers to report the cause of death continued until 1836.
Graunt recorded the incompetence of the Searchers at identifying true causes of death, remarking on the frequent recording of 'consumption' rather than other diseases which were recognized then by physicians. He suggested a cup of ale and a doubling of their fee to two groats rather than one was sufficient for Searchers to change the cause of death to one more convenient for the householders. No one wished to be known as having had a death by plague in their household, and Parish Clerks, too, connived in covering up cases of plague in their official returns. Analysis of the Bills of Mortality during the months plague took hold shows a rise in deaths other than by plague well above the average death rate, a tell-tale sign of misrepresentation of the true cause of death. As plague spread, a system of quarantine was introduced, whereby any house where someone had died from plague would be locked up and no one allowed to enter or leave for 40 days. This frequently led to the deaths of the other inhabitants, by neglect if not from the plague, and provided ample incentive not to report the disease. The official returns record 68,596 cases of plague, but a reasonable estimate suggests this figure is 30,000 short of the true total. A plague house was marked with a red cross on the door with the words "Lord have mercy upon us", and a watchman stood guard outside.
Preventive measures
Reports of plague around Europe began to reach England in the 1660s, causing the Privy Council to consider what steps might be taken to prevent it crossing to England. Quarantining (isolation) of ships had been used during previous outbreaks and was again introduced for ships coming to London in November 1663, following outbreaks in Amsterdam and Hamburg. Two naval ships were assigned to intercept any vessels entering the Thames estuary. Ships from infected ports were required to moor in Holehaven near Canvey Island for a trentine – period of 30 days – before being allowed to travel up-river. Ships from ports free of plague or completing their isolation period were given a certificate of health and allowed to travel on. A second inspection line was established between the forts on opposite banks of the Thames at Tilbury and Gravesend with instructions to pass only ships with a certificate.
The isolation period was increased to forty days – a quarantine – in May 1664 as the continental plague worsened, and the areas subject to quarantine changed with the news of the spread of plague to include all of Holland, Zeeland and Friesland (all regions of the Dutch Republic); restrictions on Hamburg were removed in November. Quarantine measures against ships coming from the Dutch Republic were put in place in 29 other ports from May, starting with Great Yarmouth. The Dutch ambassador objected at the constraint of trade with his country, but England responded that it had been one of the last countries introducing such restrictions. Regulations were enforced quite strictly, so that people or houses where voyagers had come ashore without serving their quarantine were also subjected to 40 days of quarantine.
Outbreak
Plague was one of the hazards of life in Britain from its dramatic appearance in 1348 with the Black Death. The Bills of Mortality began to be published regularly in 1603, in which year 33,347 deaths were recorded from plague. Between then and 1665, only four years had no recorded cases. In 1563, a thousand people were reportedly dying in London each week. In 1593, there were 15,003 deaths, 1625 saw 41,313 dead, between 1640 and 1646 came 11,000 deaths, culminating in 3,597 for 1647. The 1625 outbreak was recorded at the time as the 'Great Plague', until deaths from the plague of 1665 surpassed it. These official figures are likely to under-report actual numbers.