Jimmy Wilde's birth certificate states that he was born in the Taff Bargoed Valley community of Pentwyn Deintyr) (now known as the Graig), Quakers Yard, Treharris, Wales, in the county borough of Merthyr Tydfil. His parents later moved to the village of Tylorstown in the Rhondda Valley when Wilde was around 6 years old. In the 1901 census eight year old William James Wilde, his parents and his three sisters were all recorded as speaking only Welsh. His father was a coal miner and Jimmy later worked in the pits himself, being small enough to crawl through gullies impassable to most of his colleagues. He started boxing at the age of sixteen in fairground boxing booths, where crowds were amazed by his toughness and ability to knock down much larger opponents, most of whom were local men weighing around 200 lbs.