I had seen your posting when it first went on the site and didn't think it had any signicance for me.Since then I have realised that my gf Thomas Callow b1866 had a brother Amos Henry Callow b1860 and he may have dropped the use of Amos for use in official documents. Following a hunch I looked more closely at the Callow BMD info posted by Clive Callow.
I found that at my gf Thomas's wedding, one of the witnesses was Henry Callow.Obviously his brother and likely his best man.No sign of the name Amos.I then found reference to a Henry Callow b1907 at Isleworth, MDDX.His father is shown as Henry Rosam Callow and mother Sarah Shortland.
Here comes the interesting bit.My ggf George Callow (father of Thomas and Amos Henry) married an Emma Rosam.It was not unusual during the 1800's for children to have their mother's maiden name used as a forename, as in the case of Henry Rosam Callow.Do any of the names I've given ring any bells with you?
There was another brother to my Thomas and Amos Henry.He was John Francis b1862. I know nothing more about him but there is the chance he married and had children but despite a lot of research I can find no trace of him in the 1881 census.Dead or emigrated?Could he be father to your Henry, named after his own brother Amos Henry?