Anthropology blogger Dienekes puts the big new genetic study of the British in perspective

British origins (Leslie et al. 2015)

The authors write:

Consistent with earlier studies of the UK, population structure within the PoBI collection is very limited. The average of the pairwise FST estimates between each of the 30 sample collection districts is 0.0007, with a maximum of 0.003 (Supplementary Table 1).

These are extremely small differences in the European (let alone global) context. So, the British are, overall, a very homogeneous population. This is what led the researchers to use methods such as ChromoPainter/ fineStructure/ Globetrotter that can squeeze out fine-scale population structure by exploiting linkage disequilibrium. Thus, the authors are able to detect 17 main clusters of the British.

Most of the clusters are geographical, but some span different regions (e.g., the “yellow circle” cluster). The elephant in the room is the “red square” cluster which spans Central/South England. The authors write:

There is a single large cluster (red squares) that covers most of central and southern England and extends up the east coast. Notably, even at the finest level of differentiation returned by fineSTRUCTURE (53 clusters), this cluster remains largely intact and contains almost half the individuals (1,006) in our study.