Marjorie Louise Meddemmen (Auntie Marj to us young Roses).
Marjorie was Evelyn's sister, the only two children of James Edward Meddemmen and Kathleen Elizabeth Kipling.
A handwritten note on the back of the photo gives a date of 19th September 1946, The Esplanade, Jersey. We think that the seated figure in the background is Kathleen.
Thanks to my little sister Kate for scanning this picture.