Anne Grahame Johnstone artwork - Mary Finds the Secret Garden

I was lucky enough to get this picture from ebay! It is an original painting by Anne Grahame Johnstone. She and her twin sister, Janet, used to paint all their pictures together, until Janet died in 1979. This picture has the date of 1997 written on the back, so painted near the end of her life (she died in 1998). The picture is titled Mary finds the secret garden, and I havn't found it in print form, and I don't think she ever illustrated the book "The Secret Garden".