He was born in Leicester in 1934 and studied at Nottingham University before joining the local parks department and beginning the Kew certificate course in 1956.
He received the Dummer Memorial Prize for a collection of British flora and obtained the national diploma in horticulture and the diploma in parks and recreation administration.
On leaving Kew, Risley worked for the parks department at Hayes and Harlington then as assistant parks superintendent at Lytham St Anne's. In 1969 he joined the Ministry of Transport, where he worked on the landscaping and ecological management of motorways.
He later worked in the Middle East, where he specified and constructed the first natural grass football fields in the Arabian Peninsula. In 1979, he established a landscape company in Saudi Arabia.
Risley moved to Spain in the late 1980s, working on landscape projects including the Barcelona Olympics, then became a garden, sports field and landscape consultant from his home in the Wirral. He was married to Julie and had eight children.
His professional voluntary work included judging Green Pennant, Green Flag and Green Heritage projects for the Civic Trust. He was regional secretary for the Institute of Horticulture from 1996 to 2006, events officer for the Kew Guild from 1993 to 2003 and secretary from 2003 to 2006.