The growth of the population in Britain has been fundamentally driven by a process known as 'demographic transition.' It is the way the societies change as they become wealthier. First comes a decline in mortality, leading to a short population explosion; then, after an interval if variable length, a steep decline in the birth rate, which slows, halts or may even reverse the rise in numbers.
Estimates of the population at the time of the Domesday Book vary from between 1.5m to 2.25m; from these estimates it is likely that the population in Gloucestershire (including the two major towns of Gloucester and Bristol) was in the region of 40,000 inhabitants; in the Cotswolds it may have been as few as 6,000 to 10,000.
The population was highest in the south-east part of the Cotswolds and around Cirencester and it has been calculated that the population varied from about six to ten people per square mile. In a word 'scattered'. Nonetheless, the Cotswolds can be considered to have been extensively settled and cultivated by Norman times and supporting a comparatively sizeable population.
Other more densely populated areas were where mills were already becoming established along the Frome and Stroud valleys.
For most of human history, people have had lots of children of whom many died in infancy. However, if things were going well, the population would rise but then only to be checked by disease (such as the plaque or smallpox) or wars. Even the 20th century has suffered from the scrouge of disease: the world-wide flu of 1918-19 is thought to have caused somewhere between 25m-40m deaths. Since 1980 AIDS has killed 12m people.
However the Black Death in 1348 reaped some benefits for those that survived. As the population reduced demand for food slumped and so did prices. An English chronicler recorded that in the plaque year "a horse once worth 40 shillings could be bought for half a mark [one sixth as much], a fat ox for for four shillings [say, a third of its earlier value], a cow for one shilling."
But the wages did the opposite: "In the autumn a reaper was not to be hired for less than eight pence [a day, 50-75% up]. So many crops were left to die."
It did not last: the English government swiftly brought in laws to stop the free movement of labour and restore pre-plaque wage levels fining employers who paid more.
In pre industrial Britain, food crisis served as periodic population checks. Bad harvests led to an increase in prices and more people died.
In the early fourteenth century the larger villages in the Cotswolds were somewhere in the region of having 150-200 inhabitants; the smallest ones would only have some fifty people living in them.
In Gloucestershire there was depopulation during the fourteenth and fifteenth century, not only due to the affects of the plague but also to (a) the enclosure of former arable land and its conversion to sheep runs and (b) as farming methods became more efficient there was less need to farm the more exposed and barren parts of the uplands. Hence a number of villages were deserted, mainly in these remote areas. Today it is estimated that fifty villages were deserted during this time.
This was also seen nationally with the national population being around 2.2m-3.0m in 1377 but declining to barely 2.0m by the third quarter of the fifteenth century.
In the Cotswolds there was a shift from agriculture work to the wool and cloth trade. By the late fifteenth century the industry was a well established rural industry across much of the Cotswolds but by the sixteenth century the industry had largely died out in the north and east Cotswolds but was expanding around the Stroud, Painswick, Durley and Wotton-under-Edge areas with a commensurate shift in populations. In 1608, a list of able-bodied men in the County showed that in the southern Cotswolds at least 40 per cent of all male workers were engaged in the clothing industry.
But whilst in 1700, the mainland population in Britain was around 6m-7m by the time of the first official census in 1801 it had grown to 10.7m, to 20.9m in 1851 and 37.1m in 1901.
Agricultural's share of male employment fell between 1700 and 1850 from about 60% to 25%; industry's rose from under 20% to around 50% and by 1850 one in two people lived in a town or city.
In the same period, the death rate which had peaked at around 35 deaths per 1000 population in 1710, had dropped to 22 by 1850 (and today, for perspective, is around 11.)
However, during the nineteenth century there were fluctuations and indeed a slight increase in the death rate as people suffered ill health through living in over-crowded and unsanitary conditions in the burgeoning cities and, at the worst times, they were gripped by devastating cholera epidemics in 1831-2, 1848 and 1854-5.
Manchester saw it's population grow from around 10,000 in 1700 to almost 800,000 by the middle of the nineteenth century. This was Britain's first industrial city, suddenly swollen by it's cotton mills. In 1835 it was described thus:
"Heaps of dung, building rubble...one storey houses whose ill-fitting planks and broken windows suggest a last refuge between poverty and death...yet below some a row of cellars, 12 to 15 human beings crowded into each repulsive hole. Yet from this foul drain, the greatest stream of human industry flows out to fertilise the whole world, from this filthy sewer pure gold flows."
The birth rate in Britain rose gradually from 1700 when it was 30 births per 1000 population to a rate that was close to 40 births during much of the nineteenth century. There was a dramatic decline after the Great War to 14 births per 1000 and today it is 12.
(Rudder in his history of Gloucestershire published in 1779 estimated that at this time in Cirencester the average household contained "Four perfons and a half.)
There was also migration that had some affect in the population but not as great in Britain as elsewhere. In the 1850s, Britain was losing 250,000 people a year to migration to the U.S. and the colonies. There was government encouragement as they were worried that population growth would outstrip the means of subsistence. Of course there was some inforced movement like the 150,000 British convicts that went to Australia between 1788 and 1867.
Marriages in  the sixteenth century lasted, on average, only 17 years; by the eighteenth century, 22 years although not ending usually by divorce as in the 20th century but by the death of a spouse. However, many widows and widowers went on to remarry so, for example, one third of all marriages in Manchester in the 1650s were second or third marriages. So households were often filled with all manners of combinations of half- and step siblings- much as they are today.
There were also extra-marital births, the rate taking off in the nineteenth century so that by 1850 they accounted for close to 7% of births.
In Gloucestershire in 1901 the population was 708,439; England and Wales had a population of 32.5million. The density of population per square mile was 563 people/mile; the national average was 558/mile and in Lancashire it was 2347/mile. The County in 1901 was the seventeenth English county in size, and the twelfth in population.
Some 60,000 people were engaged in mainly rural industries (including 7,000 in timber related industries) and 25,000 in agriculture. Most farms were growing crops such rye, beans and peas and having permanent pasture for sheep.

Master Index

Rudders Estimate of Village Populations
When Samuel Rudder published his history of Gloucestershire in 1779 he estimated populations for the begining of the 18th century and for the 1770s. This is just a sample of his records:
 

Gloucester Villages: Population Changes in the 19th century
 

Details of todays population for the administrative district of Stroud can be found here.

Master Index