Since the Second World War the human population has trebled, from fewer that 2.5 billion in about 1950 to 7.3 billion in 2014, and now there is overwhelming evidence of worldwide overpopulation: there are about a billion people in the world for whom hunger is a daily background ache in their lives; food production is endangered by soil erosion, depletion of aquifers, the effects of climate change, the replacement of farms by ‘infrastructure’, the growing of biofuel crops, and the probable absence or unaffordability of fertilisers as oil sources become exhausted in a few decades time; we observe the ‘environmental and social problems that today afflict us and our poor battered planet’ (Sir David Attenborough’s address ‘People and Planet’ to the RSA on Google)- the extinction of species, traffic congestion, depletion of fossil fuels, human migration and immigration problems, urban sprawl, loss of arable and recreational land, unemployment, desertification, famine, air and ocean pollution, loss of rain forest, depletion of the oceans’ fish stocks; many informed people believe that human overpopulation and activity are causing climate change.

Whether or not England is overcrowded is a matter of personal judgment, but it is a fact that our country is overpopulated. The population density (number of people per square kilometre) that a country can sustain depends on the geography and fertility of the land itself, and the stage of civilisation of its people. In countries where primitive man chose to live, ‘hunter-gatherers’ achieved a density of about 0.5 people per square kilometre. Once man discovered agriculture about 10,000 years ago, this density leapt a hundredfold, to about 50 people per square kilometre. Then the arrival of industry enabled it to grow again, approximately trebling, through the availability of machinery to grow more food, transport for moving food to markets (reducing susceptibility to famine, droughts, and seasonality of crops), and the production of goods to trade and to improve our living standards.

The Sustainable Population Party claims that a sustainable population density for England is about 150 people per square kilometre. This is broadly in line with the findings of The Optimum Population Trust, now called ‘Population Matters’ of which Sir David Attenborough is a well-known patron, and the Sustainable Development Commission which was established in 2000 to help governments ‘rise above the limitations of short-term political and budgetary cycles’, and closed down by the present government in March 2011. Inconvenient truth?

England’s population density has recently grown to exceed 400. This is a convenient number to imagine, because there are precisely 400 fifty-metre squares in a square kilometre, so we get one each. It would be uncomfortable for us to try to survive in such a small space, of course; we could possibly grow enough food, providing we became vegetarian, but that fifty-metre square must also accommodate buildings, roads, recreation, waste disposal, and all the other stuff we expect as civilised people. Some people have the impression that there must be room for more infrastructure, more people, because there is lots of unspoilt countryside. But this is false: the whole population of the world would fit into England (about 20 square metres each), and nobody would argue that that would be ‘sustainable’. The fact that we have visible space is not the only criterion for further growth; it is not even an important one. It is merely evidence that we tend to group together in cities and towns. We need open spaces.

The indicators that England is overpopulated are all around us: our food production would feed only a third of us; there is constant pressure to build hundreds of thousands of new homes; our transport systems are loaded to the point of saturation so that the slightest interruption causes chaos; our beautiful city-centres are surrounded by miles of ugly urban sprawl engulfing once-pretty villages; the spaces between villages and towns are being in-filled creating faceless conurbations and destroying communities; we are constantly anxious about the decline in wild-life and habitat; an unsustainable population size results in widespread unemployment or underemployment. Anybody who doubts that England is overpopulated should take a driving holiday around the country, and then do the same in France, say, or Denmark, or any other European country, and observe the difference. (France and Denmark both have population densities below 150.)

So, if 400 people per square kilometre is unsustainable, how has it happened? The answer, of course, is historic. When our industrial revolution began, around 1750, the population of England was about 6.5million (density 40 psk); as a result of industrialisation it approximately trebled over the next hundred years to about 21million in 1850 (density 135 psk), and it continued to grow. For some 200 years, Britain was the ‘cradle of the industrial revolution’; we were mass-exporters to the rest of the world. Our industries included spinning and weaving, mining and shipbuilding, iron and steel material and goods, building canals, roads and railways, chemicals, ‘pig-iron and cheap tin trays’. Britain was the workshop of the world, and our population grew to provide the labour for all this activity. We were able to sustain a population much greater than 150 because we were net exporters on a massive scale.

The effect of this transformation from an agricultural to an industrial society is illustrated by the historic employment statistics: at the start of the industrial revolution in 1750, 65% of our active population were employed in agriculture, and by 1950 this had fallen to 5% (the lowest of all countries for which records exist). In comparison, in China in 1950, 70% of the population were still employed in agriculture, but since then China’s industrial revolution (and that of India, Brazil, and all the other countries to which we previously sent the fruits of our mass-production) has roared ahead. To illustrate the effect of this on our industry, since 1950 Britain’s population has risen from 50million to 63 million, but the number of manufacturing jobs has fallen from 8.7million to 2.5million.

Who seriously believes that we will regain our position as a major manufacturer of goods for the world? Should we just press on with growing our population as though nothing had changed? The Sustainable Population Party believes that we should adjust our plans and ambitions to this new reality. We should plan to reduce our workforce and population accordingly, or we will achieve a decline to poverty and squalor.