Henry was the son of Henry and Florence Louisa Graham nee Garnett. He had one brother, Robert (b. Bishop Thorpe York, 14 January 1902).
His mother Florence Louisa was born in Newark in 1872 (A/M/J Newark), the daughter of James and Mary Elizabeth Garnett (later spelt Garnet). She had eleven siblings. She lived with her parents in Newark but by the time of 1891 Census was probably living at 169 Cleethorpes Road, Hull, as a boarder in the household of Robert Smith and his wife. She was 19 years old and employed (occupation illegible on census).
No record of her marriage has yet been traced in the United Kingdom, but her son Henry's school record at Dulwich in 1912 gives his father's name, occupation ('independent means') and that he had 'died abroad', so the marriage may have taken place overseas.
In 1901 Florence (29) and Henry (2) were registered at a lodging house at 6 Prospect Place, Harrogate, along with Florence's sister, Margaret Annie Garnet (17) a milliner's apprentice. Florence's second son, Robert, was born the following year.
Florence was widowed by 1911 and living at 'Manhattan', Buregate Road, Felixstowe, Suffolk, with her sons Henry (12) and Robert (9) who were attending a private school, St Felix.
The brothers later attended Dulwich College and lived at 30 Chestnut Road, West Norwood.
Henry left Dulwich College in April 1916 and joined the Indian Army.
His brother Robert attended naval school and joined the Clan Line, later transferring to the Royal Naval Reserve as midshipman. He died aged 16 at the Royal Naval Hospital Plymouth on 2 October 1918 from pneumonia following influenza. He was buried in Plymouth (Ford Park) Cemetery.
Robert's record on the CWGC Debt of Honour gives his mother's address as 23 Lytton Avenue, Palmer's Green, London.
Florence was recorded at the Marina Lagos Hotel, Bexhill, Sussex, at the time the England & Wales Register was compiled in 1939. Her date of birth was given as 16 March 1872 and she was of 'independent means'.
She died at the Sherwood Hospital, Nottingham, on 20 March 1959. Probate was awarded to her married sister Margaret Annie Lyon.
Florence's youngest brother, Grosvenor Garnet (sic), served with the Canadian Infantry and later as second lieutenant in the Lancashire Regiment. He was killed in France on 9 October 1917 and was buried in Cement House Cemetery, Langemark-Poelkapelle (see record on this Roll of Honour).