Armitage was born in Surrey, the fifth of seven children born to Monica Fennell and James Armitage, an Anglican priest. Armitage’s family lived in Surrey until Armitage was eight, then moved to Derbyshire. Armitage took a secretarial course in Oxford, then moved to London to work at a photographic agency. In 1964 she moved to Bristol and worked as a personal assistant to an interior designer. She met the artist Paul Feiler, who encouraged her to undertake evening art classes. From 1967 to 1973 Armitage completed a painting degree and a postgraduate in etching at the Slade. She and Feiler married in 1970, and in 1973 they moved to Kerris, Cornwall, where their twin sons were born a year later. From this point Armitage pursued a career as an artist.
The earliest work done by Armitage took the form of landscapes completed on the spot or in the studio, still lifes and figures. Her work is based on observation, as she herself stated: “my paintings are reactions to the things I see; they are not about ideas.” Her experience at the Slade School of Art, where she was taught by Anthony Gross and Barto dos Santos, was a huge inspiration to her. During her time at the Slade, Armitage departed from the figurative and landscapes for bold, abstract, organic forms. The strongest inspiration for this transition was the work of Jean Dubuffet: “[a]fter seeing Dubuffet, it was the way I looked at things that was different.” And although she had always wanted to attempt abstract painting, it was something she did not want to force. Feiler also prompted Armitage’s changing style, stressing the importance of edges, now an essential part to Armitage’s work, with edges either defined by lines or colour, and at times an alteration in the application of the paint. Although Armitage studied etching at the Slade, she came to believe that etching lacked creative thinking, painting being her “first love.” However, the etching did draw her attention to textural difference, and her use of thin lines in her work was also inspired by experiments with etching.
The landscapes and light of Cornwall would become an invaluable source of inspiration for Armitage’s movement into more simplified forms. Her approach has been described as modernist due to the application of her oils on canvases, which stay as flat and as close to the surface as possible. Collage also played an important role in Armitage’s early work. She would cut up pieces of canvas, dying them colours that related to the tonalities of her painted work, most often pale hues. She then glued these to the same surface. However, Armitage slowly phased this out in favour of the textures and layers that oils could provide her with in terms of brushstrokes and tones, occasionally adding sand for a rougher texture. Despite leaving collage behind, Armitage has said that it was “absolutely vital” to the development of her later abstraction.
Armitage’s inspiration has always been visual. For her Waxholme series it was a large outcropping of rock in Sweden that she photographed herself. Her RD series was inspired by paintings by Richard Diebenkorn, which she saw reproduced in a book. The Dunderet series (2009) was inspired by observed and photographic material from a trip to the Arctic Circle. By the end of the 1990s, Armitage reintroduced textural elements to her work, without the use of collage, believing that her work had become “too neat, tidy and pared down.” Armitage’s most recent inspiration has been nano-photography. Armitage’s use of the visual is unchanged and her style still similar, however, in her most recent work the forms are simplified, unspecified and organic.