Born into a family with an English father and a Spanish mother, she attended the University College London to read modern languages and later studied a Doctor of Philosophy art degree under Tancred Borenius.
[1] She graduated in 1931[2] but stayed in London to do a Doctor of Philosophy degree under the art historian Tancred Borenius, completing a thesis on the followers of painter Francisco Goya in 1934.
[3] With a grant from the Leverhulme Foundation, Harris travelled to Spain to research Caravaggio's influence on 17th-century Spanish paintings combining a part-time teaching job at the Courtauld Institute of Art.
[3] In Spain Harris met art historian August Liebmann Mayer and became friends with future Museo del Prado director Diego Angulo Íñiguez and the poet Manuel Altolaguirre.
[1] Despite the time spent billeting children Harris still conducted her own research while spending six months as a tuition fellow at New York University.
[2] Harris served on the Royal Academy Winter Exhibition's executive committee of 1963–64 and produced a conglomeration of Goya-related articles which had little or unknown information about the painter.
[3] During Harris's later years arthritis made it more difficult for her to travel and work in libraries, but formed collaborative enterprises with her extensive knowledge and shrewd judgement at the disposition of younger scholars.
[2] In 1989 she received the Gold Medal of Merit in the Fine Arts from Juan Carlos I, and the Grand Cross of the Order of Isabella the Catholic in 2002.