As the mother of adopted children, I know it is possible under the Freedom of Information Act to apply for the original birth certifcate which would have named your Mum's natural mother. Although my children have birth certificates naming my husband and me as their parents, the Registrar of Births Deaths and Marriages would be able to supply the ORIGINAL certiffcate to you in lieu of to your mother, given that she is deceased. And under the same Act the hospital would have to provide you with post and pre natal reports which would also name the birth mother. We did these things when my son wanted to obtain information about his birth mother. Hoping this will assist you. But in seeking details of your Mum's birth mother, who could be and probably is still alive, you must be mindful of respecting her privacy if you intend to attempt to contact her. I have been able to supply my son with his ancestral information relating to his birth family, and we have even obtained birth death and marriage certificates. The death certificates are particularly useful because they often provide information of possible genetic health problems. We discovered he had younger half-brothers, and made the mistake of contacting one, who had no knowledge of his existence, challenged his mother about him, and many tears were shed by her and them when she had no choice but to admit the truth of my son's birth and adoption. So think careful about possible consequences before you go ahead. Good luck. Val