The Moseleys were unrepentant Fascists to the end.
However, I will cut Diana a tiny bit of slack as, from my recollection of either Nancy the novelist's bio, or the group one of the sisters, she was really good during Nancy's final illness, when they were both living in Paris. Given that Nancy had grassed her up to the Govt at the outbreak of WW2 as deeply politically suspect and Diana ended up in Holloway prison with a very small baby, maybe that counts towards a redemptive arc?