This is the Small/Smale family (clearly written as Small) on the 1851 census in Alderney
1851 census HO107 2531 folio 546
St Anne Alderney
George Small 22 Jersey, Channel Islands Head Married Mason
Selina Small 22 Guernsey, Channel Islands Wife Married
Georgia Small 1 Guernsey, Channel Islands Daughter
Wm Bowles 35 England Cousin St Anne Alderney Married Mason
plus 1 lodger
Marriages Dec 1861
Batten Caleb Stoke D 5b 578
Smale Selina Stoke D. 5b 578
Small Selina Stoke D. 5b 578
1861 census RG9 1452 folio 15
45 Granby Street Stoke Damerel Devon
Selina Small 33 Guernsey Isle Of Head Widow Housekeeper
Georgeann Small 11 Jersey Isle Of Daughter
Selina Small 7 Alderney Isle Of Daughter
Emily Small 3 Devonport Daughter
(the Henry of the 1871 census?) Marriages Dec 1876
Smale Georgina Woodward Stoke D 5b 623
Rowe Richard Stoke D. 5b 623
Marriages Sep 1879
SMALE Selina Mary Stoke Damerel 5b 552
Norton William John Stoke Damerel 5b 552
Selina is visiting her sister Georgina on the 1881 census.
This leaves the possibility of Emily/Henry being Isaac though his/her birth is given consistently as Devonport on both censuses. I can't see a birth registration for a Henry/Isaac Small/Smale between 1856-1858 in Stoke Damerel registration district. I didn't check for an Emily.
This website gives details on who to contact for information on civil registration in Alderney.
http://user.itl.net/~glen/alderney.html1841 census HO107 1461/11 folio 25 page 7
26 Hue Street Channel Islands St Helier Jersey
Mary Small 35 England Charwoman
Jane Small 10 Jersey
George Small 12 Jersey Mason ap.
Jane Finch 60 England
Thos Lea 30 England Mason
However you really do need Isaacs marriage certificate for his parents information. There were other Smalls living on Alderney at the time of the censuses.
1841 4
1851 8
1861 5
1871 3
Regards
Valda