Jack Evans - 

Jack and Mary worked together very closely within the Welsh Valleys. Jack lived in Cefn Coed y Cymmer, Merthyr Tydfil and his focus was on the Brecon and Valleys' natural and industrial heritage. Together with Clive Thomas, Mary Gillham and John Perkins, Jack wrote a trilogy of books on the Historic Taf Valleys and co-lead numerous walks with Mary. Jack also discovered the only population of Sorbus leyana (Ley's Whitebeam) in the world which currently stands at 11 mature individuals.

Jack  co-founded the Merthyr Tydfil and District Naturalists' Society with Mary Gillham in 1977.