For example, it's worth bearing in mind that the population of Roman Londinium was larger than that of London until about the 16th century, and the population o

For example, it's worth bearing in mind that the population of Roman Londinium was larger than that of London until about the 16th century, and the population of Roman Britain was also considerably larger than during most of the medieval period. Given the timber-dependent, agrarian pre-industrial economy of the Roman era, this meant an enormous amount of forest removal (military forts and structures like Hadrian's Wall alone would have accounted for a lot of this.) Thus, any notion of a truly natural landscape of forest in the British Isles disappeared since long, long before the immediately pre-industrial era. Likewise applies for much of Europe even. Again, an example: the landscapes of modern Spain, France and Italy, were repeatedly cleared of forests during their history, particularly by the Roman Empire's needs. Of course, on the other hand, you could also define natural to mean anything allowed to grow without human intervention for X number of centuries, in which case, yes, there have been many truly natural old growth forests in Europe well after Roman times, simply because they regrew during the hundreds of years between the fifth century and later, heavy population growth prior to the disastrous 14th century depopulation stemming from the Black Death and Great European Famine of the early 1300s (thought to have possibly been caused by a massive volcanic eruption somewhere else in the world)