I did a post a couple of days ago on Rhod Gilbert. There is another Welsh comedian I enjoyed listening to as a child - Ryan Davies. Sadly he passed away at the age of 40 in April 1977. He and his partner, Ronnie Williams, appeared in a Welsh language comedy on BBC - but for a couple of years, an English series was broadcast. I wish I had been able to find an episode on Youtube, but sadly I couldn't.
A short biography is available here. Having written this post, I am now going to watch the 1971 film of Under Milk Wood, in which Ryan appeared.