I do think the certificate is the only way to go. Without it you don't have George's father's name and occupation either or the witnesses and the exact place of marriage.
Coming forward on the censuses
1871 census RG10 2283 folio 43
St Mary Truro Cornwall
George Smith 68 London City, Middlesex, Head Married Hawker
Amelia Smith 55 Kenwyn, Cornwall, Wife Married
James Smith 15 St Mary, Cornwall, Son farm Labourer
Mary Smith 12 St Mary, Cornwall, Daughter
1881 census RG11 2312 folio 50
Charles St, Kenwyn, Truro Cornwall
Amelia Smith 66 Truro, Cornwall, Head Widow
Elizabeth Palmer 4 Truro, Cornwall, Granddaughter
1891 census RG12 1830 folio 46
No 4 Hoskins? Court Kenwyn Cornwall
Amalia Smith 75 Truro, Cornwall, Head Widow
Annie Palmer 10 Truro, Cornwall, Granddaughter
Deaths Sep 1894
Smith Amelia 78 Truro 5c 85
So she remains pretty consistent about her age.
Georges death is the more interesting of the two. I could find no George Smith deaths registered Truro between 1871 and 1881 so tried Slack.
Deaths Mar 1872
SLACK George 69 Truro 5c 118
which is consistent with George's age on most censuses.
Slack and Truro on FreeBMD gives you these entries between 1837 and 1872.
Marriages Mar 1842
SLACK George Truro 9 363
Births Dec 1842
Slack Ann Truro 9 312
Births Dec 1844
SLACK William Henry Truro 9 *17
Births Dec 1846
Slack Amelia Truro 9 326
Deaths Jun 1848
Slack Amelia Truro 9 200
Births Mar 1849
Slack Amelia Truro 9 369
Births Mar 1852
Slack George Truro 5c 200
Births Sep 1858
Slack Mary Truro 5c 180
Births Dec 1861
SLACK Emma Barton Truro 5c 167
Births Mar 1867
SLACK William Francis B Truro 5c 169
Deaths Sep 1870
Slack Emma Burton 8 Truro 5c 110
Slack Francis Bassett 3 Truro 5c 110
Deaths Mar 1872
SLACK George 69 Truro 5c 118
Having checked the censuses for Cornwall 1851 to 1881 Slack is a surname virtually unknown in Cornwall apart from your family in 1851. After the 1872 death entry there are no further Slack entries on FreeBMD in Truro (checked up to 1901) so it is reasonable to assume that these Truro Slack entries on FreeBMD are all in someway connected with your family.
Doing the same with the IGI you get
ANN SLACK
Christening: 06 SEP 1844 Truro, Cornwall
JAMES SLACK
Christening: 31 OCT 1855 Truro, Cornwall
MARY SLACK
Christening: 30 AUG 1858 Truro, Cornwall
all the children of George and Amelia and a singleton Slack in 1826 in a different place which probably has no connection.
George's occupation on the 1851 census is coachbuilder journeyman. Journeyman indicates he didn't have his own established business but nevertheless indicates he was a craftsman. This is very different from being a hawker on the later censuses. So it would appear something occurred between 1851 and 1861 that meant the family changed its surname from Slack to Smith at least on an everyday basis (you can call yourself any name you wish to) and finally completely to Smith after the death of George.
On the 1861 census George gives Holborn as his place of birth within London.
There is on the IGI a possible baptism at Holborn at roughly the right time, considering he moves his age around a bit.
GEORGE SLACK
Christening: 29 DEC 1803 Saint Andrew, Holborn, London
Father: WILLIAM SLACK
Mother: ANN
in all three children were baptised at the same time which doesn't mean triplets, just the family was a little lax in getting their children baptised - and therefore the George baptism could indicate an earlier birth as only one of the children is likely to have been born circa 1803.
JOHN SLACK
Christening: 29 DEC 1803 Saint Andrew, Holborn, London,
CHARLES SLACK
Christening: 29 DEC 1803 Saint Andrew, Holborn, London
with a later possible at St Pancras who might be the son of a different William and Ann
WILLIAM FRANCIS SLACK
Christening: 04 AUG 1816 Old Church, Saint Pancras, London
Father: WILLIAM SLACK
Mother: ANN
I can't see any of these as likely siblings on the 1851 census and besides you would really need George's marriage certificate for details about his father to see if this is a likely line or not.
I have done a search on the IGI for all Amelias baptised in Cornwall on the index (which of course has far from complete coverage) and can see no Amelia with a surname anything like Knortton (of course she could have had a baptism earlier or later than I checked). The marriage certificate should give further information - she might even have been a widow for instance! - which hopefully would make looking for her alot easier, but is probably just wishful thinking.
Regards
Valda
