Thank you so much, Carol, that would be fantastic. In terms of details, we don't have a lot to go on (and we don't know his birth name, Gibel and can't find a birth certificate).
According to his WWI records, his date of birth was 4/12/1886 and he was born in Hull. He was adopted by Robert Sargeant (Senior) (dob 1839 in Falmer, Sussex) and his wife Sarah Ann (nee Sempers dob 1844 in Mablethorpe), who we think lived at Ebor Terrace, Norwood Street in Hull around that time.
The family then show up on the 1891 census as living in Birmingham and my grandad, also named Robert Sargeant by this time, was with them, aged 4. So we assume he was adopted some time between Dec 1886 and the 1891 census.
Robert married my Granny, Bessie Frances Bell in 1920 in Glanford Brigg and we believe he was living with her and her parents for a while before this (not sure if that included a period before WWI but we suspect so). Granny's Mum was also a Sempers (sister of Sarah Ann).
As various members of the Bell and Sempers and Sargeant families were all living in and around Hull at the time of grandad's birth, we at first thought that perhaps Robert had been born to a family member out of wedlock and given to his adopted parents (who had no other children) and that maybe he really was Granny's cousin and that was why she destroyed all the paperwork after his death in 1950. But that now seems unlikely.
And then we realised the orphanage was just round the corner from Norwood Street and maybe Granny was just embarrassed about Robert's real origins? Robert and Bessie had two children - John (my Dad) and Marion, both now deceased. Granny told Marion on her wedding day that Robert was adopted (don't know why she chose that moment?) but I regret never following it up further with my Dad while he was still alive. Years later Marion questioned her Mum for more details but Granny refused and destroyed all papers relating to Grandad.
Anyway, it's a bit of a long shot, we know - but we'd really appreciate any help that can be offered.
Thank you both so much
Jacky