See:Selina Brace et al (inc. Chris Stringer, David Reich, Mark Thomas, and Ian Barnes)

"Population Replacement in Early Neolithic Britain"

"The roles of migration, admixture and acculturation in the European transition tofarming have been debated for over 100 years. Genome-wide ancient DNA studiesindicate predominantly Anatolian ancestry for continental Neolithic farmers, but alsovariable admixture with local Mesolithic hunter-gatherers1-9. Neolithic cultures firstappear in Britain c. 6000 years ago (kBP), a millennium after they appear in adjacentareas of northwestern continental Europe. However, the pattern and process of theBritish Neolithic transition remains unclear10-15. We assembled genome-wide datafrom six Mesolithic and 67 Neolithic individuals found in Britain, dating from 10.5-4.5kBP, a dataset that includes 22 newly reported individuals and the first genomic datafrom British Mesolithic hunter-gatherers. Our analyses reveals persistent geneticaffinities between Mesolithic British and Western European hunter-gatherers over aperiod spanning Britain’s separation from continental Europe. We find overwhelmingsupport for agriculture being introduced by incoming continental farmers, with smalland geographically structured levels of additional hunter-gatherer introgression. Wefind genetic affinity between British and Iberian Neolithic populations indicating thatBritish Neolithic people derived much of their ancestry from Anatolian farmers whooriginally followed the Mediterranean route of dispersal and likely entered Britain fromnorthwestern mainland Europe."

I guess they felt beleaguered enough that they had to release the paper early.