Welsh words are improbably long and look difficult to pronounce. Thankfully, they are easy to type.
The Langdale Axe Industry sprang up around what is now Great Langdale, England. This industry was roughly contemporaneous with the axes being produced in Penmaenmawr. In another similarity between these two areas, both seemed to like to produce megalithic structures, especially passage graves. Some of the axes made in Great Langdale and in Penmaenmawr have been found as far south as Cornwall. While this is merely speculation it would make sense that since all three of these areas are on the Western coast of the United Kingdom, that the interchange between these neolithic stone craftsman would have occurred by boats that dotted up and down the coast to facilitate trade. As is the usual case with trade, ideas and culture travel right along with the goods being transported. This could explain the similar architectural fascinations by people so far apart.