The new projections of future population growth in England released in May by the Office for National Statistics reinforced the impression of a country whose social and economic centre of gravity is moving remorselessly southward. But just how far has England ‘tilted‘ in recent decades, is the southward move picking up pace, and is it led or lagged by the movement of jobs and the supply of housing?

These are all big questions, but it turns out there is a relatively simple way to answer them (at least partially). By finding the geographic centre of each local authority district and then calculating an average ‘Easting’ and ‘Northing’ (as the X and Y values of Britain’s ‘National Grid’ coordinate system are called) using the population of each district as a weight, we can pinpoint England’s “population centre of gravity”. What’s more, we can track it over time (using re-districted population data from the Vision of Britain website), from the first Census in 1801 to the last one in 2011 and, using ONS population estimates and the new population projections, predict its location all the way out to 2039. Ideally you would do this with more data at a finer spatial scale than that of local authorities, but that’s not available for as long a time-scale as the Vision of Britain data (though in 1995 Danny Dorling and David Atkins estimated the path of the population centre of Britain between 1901 and 1991 using ward data).

Using this method, we can pinpoint England’s population centre of gravity as of 2014 to Easting 455822, Northing 274644, about 200m west of the A5 in a field that once accommodated the now-defunct Rugby Radio Station. But how far has it travelled in the last couple of centuries? Well, not very far, but it’s been an interesting journey. In 1801 the centre was about ten kilometres almost due west in a field between Rugby and Coventry, and for the next two decades that’s more or less where it stayed. Then in the 1820s it started heading north-west, picking up speed in the following decades as the industrial revolution gathered strength and both domestic and international migrants flocked to the growing cities of the North. Around the middle of the century the centre began to move north-east, and kept going in that direction, but at a slowing pace, for the next several decades.

In 1911 England reached ‘peak North’ as its population centre of gravity rested at Stoney Stanton, after which began the great movement south-east that has continued to this day. For the last couple of decades England’s population centre has travelled at a rapid pace on a route pleasingly parallel to Watling Street, the Roman road that connected Wroxeter with London and the coastal ports beyond.

If the ONS population projections are any guide it will continue heading south-east, and in a couple of years should hit Daventry International Rail Freight Terminal, which on this evidence seems very smartly located. By 2039, the last year of the projections, it should be just off the A5/Watling Street and about to cross the Jurassic Way, which follows another ancient cross-country route. More symbolically still, it will be just a few miles from the Watford Gap, which on this evidence it should cross some time in the early 2040s.

What does this circumlocutory demographic journey tell us? First, that there have been no great migrations in in England comparable to the westward expansion of the United States, as seen in the movement of its population centre from 23 miles east of Baltimore, Maryland in 1790 to 3 miles outside Plato, Missouri in 2010. Movement of that scale and speed is presumably unique to the United States as a country that grew dramatically over less than 200 years, but England’s population distribution has probably also been relatively stable compared to other European countries, due to a happy absence of major wars, famines and epidemics since at least 1801.

All that means that the movement that we have seen has probably been largely in response to the rise and fall of economic prosperity in different parts of the country. And as it happens we can also track that too, by finding the centre of gravity of people in employment from historic Census data. The earliest year this is available is 1841, at which point the employment centre was a little outside Shilton, north-east of Coventry and about two miles north-west of the population centre (indicating that unemployment rates were lower in the north-west of England than in the south-east at that point). By 1881 both centres had moved north-east and much closer together, and they tracked each other very closely until the 1950s, at which point the employment centre began to pull away south-eastwards, highlighting the rise in unemployment in the North relative to the South. By 2001 it was about 5km further south-east than the centre of population.

Why didn’t the centre of population keep up with the centre of employment? Probably because the South didn’t build enough housing. We can only calculate comparable centres of gravity of people, jobs and homes from 2001 on, but at that point the housing centre was lagging around 800 metres north-west of the population centre, which in turn was around 5km north-by-north-west of the jobs centre. Over the next 14 years they all moved south-east, but the housing centre moved the slowest. Broadly speaking, this is why we have a housing crisis: people want to move to where the jobs are, but there’s not enough housing to accommodate them all at a reasonable cost, so you get a mixture of higher housing costs, more crowding and some people choosing not to move at all.

It’s not that surprising that the growth (or decline) of the housing stock lags behind changes in the distribution of jobs and people, since homes can’t move or disappear very quickly. This lag can mean rapidly rising costs in growing cities, and then an over-supply when economic and population growth go into reverse (something demonstrated all too effectively in recent decades by the great industrial cities of the North). But local areas can still choose to build new homes more or less quickly, and right now many places that are seeing rapid growth in population and jobs are deliberately restricting the supply of new homes. And so we are where we are.

Acknowledgement for use of Vision of Britain data: This work is based in part on data provided through http://www.VisionofBritain.org.uk and uses statistical material which is copyright of the Great Britain Historical GIS Project, Humphrey Southall and the University of Portsmouth. Parts of the data are Crown copyright, adapted from data from the Office for National Statistics and licensed under the Open Government Licence v.1.0. Parts are based on historical material which has been re-districted by the Linking Censuses through Time system, created as part of ESRC Award H507255151 by Danny Dorling, David Martin and Richard Mitchell.