Glyn Jones was born on 28 February 1905 in Merthyr Tydfil, in the South Wales county of Glamorgan, the second son of William Henry Jones and his wife, Margaret Williams Jones. His mother's family had been long established in the area, while his father's people had moved from Llanybri, in Carmarthen, during the early years of the last century. Welsh was Glyn Jones's first language, although he lost the ability to speak it fluently because he lived in an area where English was commonly spoken. His education, too, was entirely in English, and it was natural that, when he began to write, English was the language he used and has continued to use. He is, nevertheless, an intensely Welsh writer. "While using cheerfully enough the English language," he wrote, "I have never written in it a word about any country other than Wales, or any people other than Welsh people...