Hi Sheena,
Yes we are certainly some sort of cousins! I think you have the relationships correct. Mum was born in Darjeeling but went to school in Worthing (where Claud and Margaret Bald retired). At least one summer she and her sister (Margaret!) stayed with Ruth and Arthur in Bangore where he was (from Mum's stories) a professor of philosophy. Mum and 'Aunt Ruth' kept in touch with Christmas letters though Mum never kept any. I have some pix of the family and a bit of info. I did manage to track your father about 10 years ago and had a reply from him.
my email is l.lyell@latrobe.edu.au and I;m happy to share more and look forward to hearing from you directly.
cheers
Leon