The number of people fluctuated wildly over these centuries. Because agricultural productivity was low the carrying capacity of the land was limited by its physical extent. This meant that in England population is estimated to have peaked around 5-6 million but then hit the buffers as famine or disease provided a natural, if somewhat severe, constraint, periodically culling an over-populated countryside.
Two peaks occurred before the 16th century in the British Isles. The first was in the time of Roman Britain in the third century when it’s been suggested the population may have been as high as between 4 and 6 million. But there was then an ill-documented outbreak of plague in the sixth century, following a period of depopulation. By the 600s the population is supposed to have fallen to well under 2 million. We have no direct evidence that Cornwall shared in this pattern. From the later 600s or 700s population generally began to rise again and this may help to explain the renewed pressure of English expansion in Devon and into Cornwall in the eighth and early ninth centuries.
The Domesday Book provides us with the first measurement of population, albeit an indirect one. It’s been estimated thst the population in England in 1086 was somewhere between 1.4 and 1.9 million, well below its Roman peak. Using the same assumptions, we get a population total for Cornwall of between 25,300 and 27,800, around the size of modern St Austell.
The next estimate is derived from the poll tax of 1377. This has led to estimates of between 2.2 and 3.1 million for England. Again, on the same basis the Cornish population had risen to between 54,000 and 76,000. In other words, while the population of England was between 50% and 65% higher than in 1086, the population of Cornwall had more than doubled. This could of course be the result of under-counting in 1086, and it’s possible that Domesday Book missed more households in recently conquered and Celtic Cornwall than in the English heartlands. On the other hand, it may indicate that Cornwall, underpopulated in 1086, really did experience a much greater relative growth as land was brought into cultivation and resource limits were not so stressed. For instance, we know that in England from 1315 to 1322 there was an agrarian crisis in many areas, with famine reducing the population by up to 10%. Perhaps this didn’t happen in Cornwall.
But 1377 wasn’t the peak of the medieval population. That had occurred in the early 14th century, before the Black Death seared across the land, leaving in its wake piles of corpses and a people wondering what on earth they’d done to deserve this particular example of God’s wrath. It’s estimated that the population in 1347 – before the Black Death struck – was between 55% and 80% higher than in 1377. So the question has to be did Cornwall suffer from this plague at the same level as did England. And the answer seems to be yes. More than half the clergy in Cornwall succumbed, and so did half the tenants on two east Cornish manors. These proportions were about average for the British Isles.
The graph below brings together the most plausible estimates of pre-Census population for England and Cornwall and expresses them as an index based on the Domesday population.
It seems that the Cornish population rose faster than that of England in the 12th and 13th centuries to peak at around 107,000 but was then equally reduced by the Black Death, to somewhere around 65,000 by the late 14th century. But what happened between the Black Death and the mid-17th century? It’s been estimated that the population of Cornwall in 1569 was 61,000. If that was the case then in Cornwall a renewed rise in population, seen in England from the 1510s or 1520s at the latest after an extended period of depopulation during the 15th century, did not begin until two generations later. Either that, or the estimate for 1569 is far too low.
There is some evidence that a labour shortage continued in Cornwall to the late 1400s. For example adventurers in tin mines were complaining of the difficulty of finding labourers and the influx of Breton craftsmen and servants at the end of the 15th or beginning of the 16th century – the so-called second Armorican return, the first being those Breton nobles who accompanied William of Normandy in the 11th century – may suggest a continuing demand for labour.
On the other hand, Cornwall is supposed to have been economically more bouyant than average in the 15th century and comparisons of the taxable wealth in 1334 and 1515 shows that Cornwall was one of those places enjoying the most impressive relative rise. It would seem unlikely that relative rising prosperity in this period would be associated with relatively falling population. My own estimate for the population of Cornwall in the 1520s suggest a population of between 52,000 and 77,000. If we take a mid-point of 64,000 then the Cornish population is likely to have been over 70,000 by 1569. This means that it grew slightly less fast than that of England to 1660, to reach 98,000 by that year.
Then, after 1660 things began to change. In the next 100 years the Cornish population rose by more than a quarter, to around 124,000, to reach a new historic high. This was a growth that was twice as fast as that of England, a relatively faster rate of growth that was sustained into the 1780s. This accompanied a shift in population from the east to the west, unmistakeable symptom of the early industrialization of Cornwall based on the west.