[Makes us, in the SW peninsula, “northerners”]

Or should it be where Morrisons meets Waitrose? 

[Categorising us as “southerners”]

This tongue-in-cheek analysis aims to highlight more serious factors highlighting the North-South divide, such as life expectancy, education, and poverty.

(See original article: a Machine Learning analysis of consumer habits as a metric for the socio-economic North-South divide in England) – Owl

Some say it’s the Watford Gap services, some say it’s the Severn-Wash line — but isn’t the true marker of arrival in the north the moment you reach a place where you can’t get a smashed avocado and roasted pepper baguette but can get an impressive variety of sausage rolls?

Tom Whipple www.thetimes.co.uk 

That is the contention of mathematicians, who have calculated the location where the writ of poncey southern Pret a Manger sandwiches ends and the rule of honest northern Greggs pies begins — and they have declared it the north-south divide.

And, lest the analysis seems flimsy, they have strengthened it by augmenting it with a separate set of strongly correlated data: the Waitrose-Morrisons Index.

As far as Sophie Maclean, from King’s College London, is concerned, this study ends a discussion that arguably began with William the Conqueror, who noticed that the residents in the north of his kingdom were more unruly and, “In mad fury . . . descended on the English of the north like a raging lion.”

Which were these recalcitrant northerners who resisted the raging lion? Where was their unruly land? “There’s a lot of debate but thankfully mathematicians have worked this out,” said Maclean, speaking at the Cheltenham Science Festival. “Really there is only one way to judge what’s north and what’s south and that is by looking at the distribution of Pret and Greggs.”

The analysis, published in the preprint journal ArXiv, used machine learning to define the optimal north-south boundary, seeking to divide the country in two according to the ratio of Prets to Greggs and, separately, Waitroses to Morrisons. Then, researchers combined the two.

This produced a line that cut off the top of Norfolk and all of Cornwall and Bristol, decreeing these traditionally southern regions spiritually and culinarily northern.

Part of this may be explained by the metric failing in the west country. While most of the country has a preponderance of one of the fast-food chains or another, Cornwall is low on Prets, possibly on socioeconomic grounds, but also resists Greggs, on grounds of pasty-purism.

Less controversially, further east the line confirmed conventional intuition — passing close to the Watford Gap.

Dr Robin Smith, from Sheffield Hallam University, led the study, adapting machine-learning techniques normally used to look at nuclear reactions. He said that in an inevitably subjective area, this analysis was as good as any. “The food we eat is a very good indicator of whether someone is northern or southern. Greggs is very popular in the north, where people do seem to prefer a steak bake.”

The new definition will nevertheless provoke some disquiet, possibly vigorously so. Cheltenham residents, for instance, who like little better than meeting on a Saturday morning in Waitrose to pick up “essential” parmigiano reggiano, might at the very least argue the case they are an exclave of the south.

Maclean conceded there would always be anomalies, but then the same goes for any other measure. There was even sometimes a pathos to the data, where you can see the anomalies in action — for instance in the few individuals trying to eke out a sophisticated culinary lifestyle amid the pastry-based wastelands of the north.

“You could imagine the single Pret in Newcastle surrounded by a swarm of Greggs,” she said. Whereas, she added, “In London, they say you’re never more than 6m from a rat, or a Pret.”

How long this might still be the case, though, is unclear. Smith said there were signs the usefulness of the metric might change. Already, Greggs has begun a southern invasion, with an appeal to more liberal metropolitan tastes. “Since Greggs produced the vegan sausage roll, it has become more popular in the south, so this might not be a marker of northernness for that much longer.”