RootsChat.Com

No I hadn't heard of the Watt Library.  Thanks for the link. 
I have been warned by many that it is possible that the parents never registered the children.  It seems unlikely that the entry pages for all would be unreadable unless the whole book had been destroyed. 
I've also considered the possibility that Greenock wasn't Andrew's birthplace but the place he was living at the time he left Scotland.  If that is the case, he could have been born anywhere
From the 1851 census for Adam, Sarah and the 3 children remaining at home, the children's birthplace was listed as Paisley.  That leaves me no doubt that the convict was from this family, but no proof that they were the family of my Andrew.   
He may remain a mystery, unless I get a DNA match to descendants of a sibling or cousin.
Thanks for all the information.

I've been studying them for years.  Some I have matched to other wives. Some not.  The one I have my eye on is the last one you mentioned.
"There is a fourth Andrew Millar in Paisley in the 1841 census, aged 15, son of Adam Miller and Sarah. He's recorded as 15, but in 1841 adults' ages were supposed to be rounded down to the nearest 5 years so he could be anything from 15 to 19, so he's a bit old to be your Andrew, but his baptism isn't in the surviving records".
My Andrew was born about 1825/26.  I am working on the information he himself provided when he completed my gt grandmother's birth record in 1869.  He recorded his age as 43 and birthplace as Greenock.  Figured that he knew more about himself than William, who completed his death record and had him from Glasgow.
Andrew s/o Adam and Sarah was a convict transported to Tasmania in 1843.  I've managed to trace the convict up to 1849 in Tasmania but then no trace.  That give four years between the convict and Andrew and Janes marriage in Jan 1853.
Having read the report and court appearance for three of his children (Albert Emma and Minnie) after they were caught for begging and theft, he doesn't seem to to have been a nice man.  Still, I cannot claim the convict until I can fill in those last 4 years.
My gt grandmother was Emma Ann b. 1869.
I was talking to an old Scot a while ago and he suggested that Andrew may have actually been from Port of Glasgow and William mixed the two up when completing the death record.  Port of Glasgow is only about 4 miles from Greenock on the Abbey side.  A lot of baptisms seem to have taken place in Abbey.
Email me directly if you like defect@outlook.com.au

Just came across this old post of mine.  For those still looking.  The problem of who his parents were has been solved.  He was the son of Richard Conduit-BLAKE b.1788 Durnford and Judith (Julia) SMITH b. 1790 Durnford.  Both parents died 1831 and were buried in West Harnham, Wilts. 
As near as we can work out, Richard was a Miller and living at the Old Mill in West Harnham.  The mill was on the West Harnham side of the border with Fisherton Anger and the dwelling on the Fisherton Anger side with the border running through the middle of the property. 
Though John's actual baptism has not been found, the baptisms of 4 younger siblings have been found at St Edmunds Church St, Wesleyan, Salisbury.  The burials of a 5th sibling born 1819/20 and the youngest child found in the 4 baptisms at the church in West Harnham. 
Baptism records for the St Edmunds church in Salisbury can only be found from about 1821 onward.  Hence John and any children born before 1821 have not been found.
The baptism of John's eldest sister, Harriet, took place in Durnford in 1809 as Harried Conduit BLAKE.
Their father Richard Conduit BLAKE 1788-1831 was the illegitimate son of Richard CONDUIT 1766-1832 and Mary BLAKE b. 1767.  DNA matches to descendants of Richard's children through his subsequent marriages have proven the connection.
Though Harriet was baptised as BLAKE in Durnford, Richard seems to have reverted to his father's surname once he moved to the Fisherton Anger / West Harnham area and the church they used for baptisms seems to have been St Edmunds Church St, Wesleyan, Salisbury.
Hope this helps those still looking for info.

By the time of the 1841 census, Auguste was back living in Guernsey and married again to Sophia (surname unknown).  She must have died between 1851 and 1871.  Most likely between 1851 and 1861.  By 1871, Auguste had married again to Mary Judith Le Page, d/o James Le Page and Rachel Tabel (Rachel was my gt x 3 grandfather's sister).

1841:  Commercial Arcade, St Peter Port, Guernsey
A B   Goupillot   38   1803   Grocer   France
S   Goupillot   30   1811      Guernsey
Anne   Goupillot   7   1834      Guernsey
L   Goupillot   3   1838      Guernsey
Augustine   Goupillot   2   1839      Guernsey
Judith   Ozanne   16   1825   Servant   Guernsey
George   Dodd   17   1824   Servant   Guernsey

1851:  2, St James Road Victoria Place, St Peters Port, Guernsey
Auguste   Goupillot   Head   48   1803   Grocer Employing 2 Men   France
Sophia   Goupillot   Wife   40   1811   Domestic Duties   St Peter Port, Guernsey
Ann   Goupillot   Dau   17   1834   -   St Peter Port, Guernsey
Louisa   Goupillot   Dau   13   1838   Scholar   St Peter Port, Guernsey
Augusta   Goupillot   Dau   11   1840   Scholar   St Peter Port, Guernsey
Isabella   Goupillot   Dau   7   1844   Scholar   St Peter Port, Guernsey

1861:  13, Fountain Street, St Peter Port, Guernsey
Auguste   Goupillot   Head   60   1801   Grocer Employing 3 Men   France (British Subject)
Isabella   Goupillot   Dau   17   1844   House Keeper   St Peter Port, Guernsey
Rosa   Goupillot   Dau   14   1847   House Keeper   St Peter Port, Guernsey
Alfred   Goupillot   Son   12   1849   Scholar   St Peter Port, Guernsey
Phidorah   Goupillot   Dau   9   1852   Scholar   St Peter Port, Guernsey
Augustus   Goupillot   Son   7   1854   Scholar   St Peter Port, Guernsey
Thomas   Goupillot   Son   6   1855   Scholar   St Peter Port, Guernsey
Note:  Auguste is recorded as Married but wife not with him.

1871:  Fountain Street, St Peter Port, Guernsey
Auguste   Goupillot   Head   68   1803   Grocer employing 1 man   France
Mary   Goupillot   Wife   40   1831   -   Vale, Guernsey
Thomas   Goupillot   Son   18   1853   Seaman   St Peter Port, Guernsey
Rachel   le Page   Mother-In-Law   69   1802   Annuitant   St Peter Port, Guernsey
Rachel   le Page   Servant   45   1826   General Servant Domestic   St Peter Port, Guernsey

Fantastic, Thank you.  I've fund my way in as far as the blue plus sign.