He was baptized at Llandysilio Parish Church on 16 Oct 1864, the illegitimate son of Elizabeth Jones.
Hi Daisy59, Sorry, I forgot to mention one thing about this baptism - Elizabeth Jones' abode was given as Beudy. Based on this, and the other information in my first post, I believe this is the Henry Jones, age 6, living with his grandparents at Beudy, Menai Bridge in 1871.
But I do not know whether this is the same Henry Jones who is living at Bryn pilot, Llandegfan in 1881 and 1891 and who is described as the son of Hugh Jones and Jane.
I've searched Anglesey BMD indexes, census and other data for members of these families looking to see whether there is evidence to link them. But it is difficult - too many Joneses with the same first names, as you say.
Starting with Hugh Jones and wife Ellin at Beudy, Menai Bridge in 1871, they are living at Barracks, Menai Bridge in 1861 and 1851. The household in 1851 consists of:
Hugh Jones 41 Boatman b. Llandysilio
Ellen Jones 41 Wife b. Llanllyfni, Caernarvonshire
Thomas Jones 20 Son, Tailor, b. Llandwrog
Jane Jones 15 Dau. b. Llandysilio
Elizabeth 9 Dau. b. Llandysilio
Hugh 3 Son b. Llandysilio
The births of the younger children were registered:
Hugh Jones son of Hugh, mother Ellin Griffith 1 Nov 1847 - Llandysilio
Elizabeth Jones dau. of Hugh, mother Ellen Griffiths 2 Nov 1841 - Llandysilio
There was also:
Hugh Jones son of Hugh, mother Ellen Griffiths 4 May 1840. His death was registered:
14 Nov 1840 at Llandysilio, age 6 months. Informant Ellen Jones.
Hugh Jones (Llandysilio) married Ellen Griffith (Llandegfan) at Llandegfan Parish Church on 30 Nov 1830. Both signed by mark.
Ellen Jones died 30 Nov 1871, age 66 at Beudy, Llandysilio, wife of boatman Hugh Jones. Informant Elizabeth Jones.
As for the family of Hugh Jones and Jane at Bryn pilot, Llandegfan:
David Evan Jones, son of Hugh and Jane Evans born 7 Nov 1874, Llandegfan
Mary Jones, dau of Hugh and Jane Evans born 24 Aug 1880, Llandegfan
John Jones, son of Hugh and Jane Evans born 10 Mar 1863, Llandegfan
There is no Henry Jones registered as born to them but there is an un-named son:
(boy) Jones, son of Hugh and Jane Evans born 10 Jan 1866, Llandegfan who would be 15 in 1871.
Marriage:
Jane Evans of Bryn Pilot, Llandegfan, dau of John Evans, Labourer married Hugh Jones, mariner of Cefndu Bach, Llandegfan son of Hugh Jones, Labourer on 19 Jul 1861 at Llandegfan Church.
Hugh Jones and Jane are also at Bryn Pilot in 1901 and 1911. Hugh consistently gives his place of birth as Penmynydd, Anglesey. In the 1861 census he is an A B seaman on a vessel called Brian Boru (perhaps) in Holyhead harbour.
Jane Jones died 20 Jan 1908, age 67 at Bryn Pilot, Llandegfan, wife of master mariner Hugh Jones, who was the informant.
Hugh Jones died 6 Sep 1914, age 79 at Llanddaniel-fab, master mariner. Informant D.E. Jones, son.
To sum up I don't think I've got much further, it looks like the Henry Jones with his grandparents in 1871 is not the same Henry Jones who was with his parents in 1881 and 1891 but which is your husband's great-grandfather (if either?) is not clear to me. The marriage certificate Henry Jones/Elizabeth Williams might give us some helpful information, as would the 1871 census for Hugh, Jane and Henry Jones.
I hope I haven't confused the situation,
Regards