(b Swansea, 12 Jan 1810; d Swansea, 24 Aug 1882). Welsh photographer and chemist. He typified the scientific gentleman amateur who embraced the new art of photography. From its earliest days he experimented with the daguerreotype alongside Antoine Claudet. Most of his early photography documents facets of life on his estate of Penllergare in West Glamorgan. It was in the 1850s that Llewelyn’s influence in the British photographic community fully emerged. He was an accomplished landscape photographer himself, and through his oxymel process he addressed the problems peculiar to field photography. Oxymel (a pharmacist’s mixture of honey and vinegar) produced a stable photographic plate that circumvented the need to carry a laboratory into the field. Llewelyn was a pioneer of instantaneous photography and a founder-member of the Photographic Society of London (later the Royal Photographic Society).