I have lost Bertram and his parents from 1891 onwards.
His parents were George and Esther (George's second wife) who in 1890 were imprisoned for 6 months with hard labour for wilful neglect of a child under 14.
This could cover Bertram or any of his half siblings, Jeanne, Winifred and Edward who were all under 14 at the time.
I have no idea where Bertram, George or Esther have gone after the 1891 census in Battersea where the family are all back together after the parents came out of prison (RG12 431 92 44).
Edward, Winifred and Jeanne all get married and have families before 1911 but Bertram and his parents have disappeared although I think that Esther marries again in 1902 in Steyning, Sussex (where her stepdaughter Jeanne 'marries' - but this another story as her marriage to her husband Louis Dent is registered in Wandsworth in 1898 and again in Steyning in 1904)
Thanks
Ruth