These include letters from Gustav Holst to Isobel Holst, Mary Lediard, Maja Kjohler, Vally Lasker, Amy Kemp, Dorothy Callard, Edwin Evans, Dora Herbert Jones, Gwen Davies and others.
These letters have been digitised and each letter can be viewed from the catalogue record.
For letters from Gustav to Imogen Holst see HOL/2/8/2/104