Why do you keep referring to him as Henry - when marriage, census, all show him as William?
It makes it very confusing when trying to search for you.
I personally think the father shown on the 1888 marriage certificate as William Henry Backler, baker, is fictitious, and that at 29 (bc.1859) he's knocked off some years as his wife considerably younger.
In 1881 he states he is 29 i.e. bc.1852 and think this age is the closest to the truth and that he is the Willm Batcheler 8 with mother Amelia (bc.1835) and sister Emma 2 in Stapleton 1861.
Amelia was actually born 1832 and baptised 21/10/1832 Bristol, dau.of William Batcheler and wife Mary (plus a brother William bp.15/10/1837. In 1841 Mary and these 2 children are shown as Batchler and looks like husband William had died.
A William Bachellor birth reg'd Jun.1851 Bristol - illeg. per GRO index - and think this is the son of unmarried Amelia and 'your' William.
I believe the 1881 census - in which he had no need to lie - is the most accurate i.e. 29, bc.1852.
For certain, he is definitely not the son of a William Henry (a baker like himself) who never existed, and definitely not the son of William Henry b.1844 who was never a baker, never married, and too young to have fathered your man.
Annette