The latest instalment of our weekly series, in which we use the Centre for Cities’ data tools to crunch some of the numbers on Britain’s cities. 

Hell of a graph here, which tells us a lot about internal migration in Britain. It takes some unpacking though so bear with me:

The different bars represent four different groups of UK cities arranged by size (London, as ever, is in a class of its own). The colours are different levels of qualification, and where they sit on the bar shows inward or outward migration: bits above the line mean people moving in, bits below mean people moving out.

What the graph shows is that London is weird. The three other groups of cities all receive inward migration from the rest of the country: more people move in than move out. (This is not necessarily true of every individual city, of course, but is true of the groups as a whole.)

London, though, is the other way around: the city keeps growing because of international arrivals. Bits are more likely to leave than to arrive. 

The capital is weird in a different way too – because while the British people as a whole are on balance more likely to leave, graduates are flocking to London. Other cities see net outflows of graduates – as students leave universities, or older people move in search of work. London, though, is clearly a big destination – the big destination – for those people. 

This matters. Because, in the high value globalised knowledge economy which politicians like to bang on about, attracting and retaining graduates is a pretty big deal. At the moment, London is sucking up all that talent: the capital accounts for 19 per cent of all jobs, but 22 per cent of new graduates, and 38 per cent of those with a good degree from a Russell Group University.

One side effect of this, one suspects, is that house prices go up, and everyone else becomes more likely to leave.

All of this comes from the latest Centre for Cities report, the Great British Brain Drain. Here’s another graph, which drills down into figures for individual cities:

Click to expand.

Almost every city, in fact, is losing graduates. In many cases, one suspects, because they’ve finished their degrees and move for work. That’s why cities with two or more universities – from Birmingham and Sheffield to Oxford and Cambridge – tend to be losing the most 

A handful of cities, though, did see a net increase in graduates in 2010-11. They include some new towns – Milton Keynes, Warrington, Swindon – which tend to combine good jobs, affordable housing, and not having a university for people to graduate from. Bournemouth and Worthing saw a net influx too, perhaps representing the appeal of retiring to the seaside.

These ones show movement by age. Spot the odd one out:

Click to expand.

People hit 30 and leave London. Can’t imagine why.

One last graphic: this one’s an interactive map. It shows the “graduate gain” each city had in 2014 – that is, the total number of graduates who arrived within six months of completing their studies. It’s not per capita, so big cities tend to show the biggest gain:

But nonetheless, the economic subtext yells at you. Most southern cities show net gains, even if they’re tiny (though one suspects this is more likely to reflect people returning home from university than people moving to, say, Ipswich for work). But while the big northern cities are doing okay, graduates are leaving to northern towns. As graduates move en masse to London, they’re abandoning Middlesbrough and Bradford.

The Centre has produced a whole new interactive dataset, if you fancy exploring this topic more. You can play with it here.

Jonn Elledge is the editor of CityMetric. He is on Twitter, far too much, as @jonnelledge.

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