Not to any degree that I know of. Almost all English with a little bit of Irish. HPL admired Arthur Machen, a Welshman, greatly.
REH brought up the fact (in WT) that HPL had used Gaelic (as opposed to Welsh/Cymraeg) as the "primal" tongue in Britain for his classic The Rats in the Walls. HPL was amazed anyone had spotted that and started the correspondence.
Somewhat disjointed article about recent skeleton find under an Irish pub:
"“The DNA evidence based on those bones completely upends the traditional view,” said Barry Cunliffe, an emeritus professor of archaeology at Oxford who has written books on the origins of the people of Ireland.
DNA research indicates that the three skeletons found behind McCuaig's are the ancestors of the modern Irish and they predate the Celts and their purported arrival by 1,000 years or more. The genetic roots of today's Irish, in other words, existed in Ireland before the Celts arrived.
“The most striking feature” of the bones, according to the research published in the Proceedings of the National Academy of Science journal, is how much their DNA resembles that of contemporary Irish, Welsh and Scots. (By contrast, older bones found in Ireland were more like Mediterranean people, not the modern Irish.)"