Rankle takes as his main subject the development of landscape art as a concept related to changes in attitude to the environment. In some works he treats the entire history of landscape painting almost as a found object; manipulating and cross-referencing styles and techniques from diverse periods and cultures, within a post-modernist fusion of abstract, trompe l'oeil, and figurative imagery. In "Landscapes for the North" Maidstone Museum 1996 he states: "Styles are emblems of the ways we can shift our attention".
From 1973 feeling that his work, while well informed by conceptual art practice, lacked a realistic visceral dimension, he immersed himself in a study of the techniques of 17th Century Dutch Masters, the Abstract Expressionists and significantly the Ch'an (Zen) painters and calligraphers of China. During 1973-76 he studied Taoist and Ch'an Buddhist Arts, including T'ai Chi Ch'uan, with Dr. Liu Hsiu Chi. Fellow students at the Liu Academy included the musician Frances Monkman, and Fritjof Capra author of 'The Tao of Physics.' During this time Rankle's pursuit of his interests in Old Master painting led him to further studies and later employment in the field of art conservation.
Following a group exhibition at LYC Gallery in Cumbria, with Andy Goldsworthy and Michael Jepson; Rankle's work in landscape art became starkly politicised. In the summer of 1982 on his first trip to Finland he became aware of the effects of acid rain on the lakes and forests of Scandinavia, and the patently inadequate response of the establishment. A series of landmark installation/performance pieces followed intended to draw attention to environmental issues (often as fund raising events for Arts for the Earth, the art 'wing' of Friends of the Earth). These included a 30 metre long scroll painting produced on the top of Beachy Head in Sussex with his collaborator Jan Stephens, and several notable pieces with the left-field artists group Order out of Chaos; one of which 'Discarded Sculptures' (1986) was the first project to bring his work to the attention of a wider public.
A period of activism in which he attempted to work within the existing mores of the conventional art world culminated in 'Earthscape' (1991), a large scale performance/installation created in the form of an International Competition on a theme of 'Environmental Solutions' where artists were invited to submit works implying a positive response to the burgeonning environmental crisis. Curated with Christine Goldschmidt for the Hastings Trust, this project involved a wide range of collaborators including Mike von Joel, Laetitia Yhap, Andrew Graham-Dixon (who were the judges of the competition), Art-in-Ruins, Lynne Green, Nick Wates, and the book and exhibition designer Jeremy Brook.
Since his 1993 exhibition 'Riverfall & Other Works' at Southampton Art Gallery, Rankle has concentrated on painting, with notable exhibitions at Maidstone Museum; Radicev Museum, Saratov, 1996; Danielle Arnaud/Clink Wharf Gallery, 1998; Folkstone Museum, 1999; as well as numerous gallery shows in Europe, Scandinavia, and USA.
A first Retrospective Exhibition 'Landscapes for the Turning Earth' was held at Gallery Oldham 2006/7.