Quote (Wyrmvater @ Dec 15 2018 06:39pm)
although I think the Continental Celts had L-21 and invaded the Isles a long time ago:
The Proto-Italo-Celto-Germanic R1b people had reached in what is now Germany by 2500 BCE. By 2300 BCE they had arrived in large numbers and founded the Unetice culture. Judging from the propagation of bronze working to Western Europe, those first Indo-Europeans reached France and the Low Countries by 2200 BCE, Britain by 2100 BCE and Ireland by 2000 BCE, and Iberia by 1800 BCE. This first wave of R1b presumably carried R1b-L21 lineages in great number (perhaps because of a founder effect), as these are found everywhere in western, northern and Central Europe. Cassidy et al. (2015) confirmed the presence of R1b-L21 (DF13 and DF21 subclades) in Ireland around 2000 BCE. Those genomes closely resembled those of the Unetice culture autosomally, but differed greatly from the earlier Neolithic Irish samples. This confirms that a direct migration of R1b-L21 from Central Europe was responsible for the introduction of the Bronze Age to Ireland.
a simple "yes" would have sufficed.