[2] While teaching she studied in the evenings at Birkbeck, University of London, obtaining a first class B.Sc.
She was awarded the 1986 Frink Medal from the Zoological Society of London: "for her contributions to the understanding of the developmental biology, physiological ecology and functional morphology of the prosobranch molluscs".
[3][4] British Prosobranch Molluscs was originally published in 1962 by The Ray Society, and republished in a revised and updated edition in 1994.
[6][7][8] She joined the Conchological Society of Great Britain & Ireland in 1966, and remained active in research at the University of Reading until her death.
[9] In 2001, Fretter and Ruth Turner were honoured by the symposium 'New Frontiers in Functional Morphology of Molluscs', held at the second World Congress of Malacology in Vienna, Austria, in August of that year.