Well, the pre-print of the paper is out and it’s massive in its scope and in its implications.

The Beaker Phenomenon and the Genomic Transformation of Northwest Europe

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New Abstract:
Bell Beaker pottery spread across western and central Europe beginning around 2750 BCE before disappearing between 2200-1800 BCE. The mechanism of its expansion is a topic of long-standing debate, with support for both cultural diffusion and human migration. We present new genome-wide ancient DNA data from 170 Neolithic, Copper Age and Bronze Age Europeans, including 100 Beaker-associated individuals.
In contrast to the Corded Ware Complex, which has previously been identified as arriving in central Europe following migration from the east, we observe limited genetic affinity between Iberian and central European Beaker Complex-associated individuals, and thus exclude migration as a significant mechanism of spread between these two regions.
However, human migration did have an important role in the further dissemination of the Beaker Complex, which we document most clearly in Britain using data from 80 newly reported individuals dating to 3900-1200 BCE.

British Neolithic farmers were genetically similar to contemporary populations in continental Europe and in particular to Neolithic Iberians, suggesting that a portion of the farmer ancestry in Britain came from the Mediterranean rather than the Danubian route of farming expansion.
Beginning with the Beaker period, and continuing through the Bronze Age, all British individuals harboured high proportions of Steppe ancestry and were genetically closely related to Beaker-associated individuals from the Lower Rhine area.
We use these observations to show that the spread of the Beaker Complex to Britain was mediated by migration from the continent that replaced >90% of Britain's Neolithic gene pool within a few hundred years, continuing the process that brought Steppe ancestry into central and northern Europe 400 years earlier.

[...]

Individuals from the Iberian Peninsula carried Y haplogroups known to be common across Europe during the earlier Neolithic period such as I2a (n=3) and G2 (n=1) (Supplementary Table 3).
In contrast, Beaker-associated individuals outside Iberia (n=44) largely carried R1b lineages (84%), associated with the arrival of Steppe migrants in central Europe during the Late Neolithic/Early Bronze Age. For individuals in whom we could determine the R1b subtype (n=22), we found that all but one had the derived allele for the R1b-S116/P312 polymorphism, which defines the dominant subtype in western Europe today.
Finding this early predominance of the R1b-S116/P312 polymorphism in ancient individuals from central and northwestern Europe suggests that people associated with the Beaker Complex may have had an important role in the dissemination of this lineage throughout most of its present-day distribution.

[…]

We find that the great majority of Beaker Complex individuals outside of Iberia derive a large portion of their ancestry from Steppe populations (Fig. 2a), whereas in Iberia, such ancestry is absent in all sampled individuals, with the exception of two (I0461 and I0462) from the Arroyal I site in northern Spain.

[…]

We grouped individuals from Iberia (n=19) and from outside Iberia (n=84) to increase power, and evaluatedthe fit of different Neolithic/Copper Age groups with qpAdm under the model: Yamnaya + Neolithic/Copper Age.
For Beaker Complex individuals from Iberia, the best fit was obtained when Middle Neolithic and Copper Age populations from the same region were used as a source for their Neolithic farmer-related ancestry, and we could exclude central and northern European populations (P < 4.69E-03) (Fig. 2c).

Conversely, the Neolithic farmer-related ancestry in Beaker Complex individuals outside Iberia was most closely related to central and northern European Neolithic populations with relatively high hunter-gatherer admixture (e.g. Globular_Amphora_LN, P = 0.14; TRB_Sweden_MN, P = 0.29), and we could significantly exclude Iberian sources (P < 3.18E-08) (Fig. 2c).

These results support largely different origins for Beaker Complex individuals, with no discernible Iberia-related ancestry outside Iberia.

[…]

Derived alleles at rs12913832 (SLC45A2) and rs16891982 (HERC2/OCA2), which contribute to reduced skin and eye pigmentation in Europeans, dramatically increased in frequency during the Beaker and Bronze Age periods (Extended Data 277 Fig. 5).

Thus, the arrival of migrants associated with the Beaker Complex significantly altered the pigmentation phenotypes of British populations.

However, the lactase persistence allele at SNP rs4988235 remained at very low frequencies in our dataset both in Britain and continental Europe, showing that the major increase in its frequency in Britain, as in mainland Europe, occurred in the last 3,500 years.
There's much more to the paper but this should suffice for the moment, perhaps I'll make a thread of its own for it.

The predominance of R1b-P312 is really interesting. They also detected a single R1b-U106, a line presumably, predominantly Germanic, in the Netherlands, where its frequency peaks nowadays.

The absence of I1-M253 is still striking, though. For all its dominance in Scandinavia and importance in the other Germanic countries, so far it has only been found once and not even in the North but in Hungary, in a farmer context(!).