I'd love some advice on breaking through this apparent dead end.
The earliest event I can trace back to is the following marriage:
Register of Contracts 1801
Nov 14th - John MUFFET, lawful son to James MUFFET of Sandness, and Lillias JAMIESON, lawful daughter to James JAMIESON in Goster, Walls, were contracted in order for marriage Nov 14th 1801 and were married December 1st 1801 by the Rev McThompson. If we assume that John & Lillias were aged 16 - 30 when they married, then we should expect to find their birth registrations around 1770 - 1785. There are no registrations in Shetland for a John Muffet son of James Muffet, nor a Lillias Jamieson daughter of James Jamieson. If we assume James Muffet fathered John Muffet in his 20s, then James Muffet was probably born around 1750ish. If we then assume he lived till about 70-80 then he probably died around 1820-1830. The closest record for a James Moffat death in Walls occurs in 1850, where a James Moffat died aged "about 80". This would make him roughly the same age as his son, so must be ruled out.
When I hired a genealogist years ago he came back saying that I should ignore the James, and that he thinks this John is the same John that was born 1 August 1782 in Papa Stour, the son of Henry MOFFAT and Marion HENRY. This couple certainly existed, and they did have a son called John. He also mentioned something about Mormon batch numbers, whereby the Mormon records had linked the 1801 John to the 1782 John.
When I looked around online I found my John in 3 different databases. 2 give his father as Henry, 1 gives his father as James:
http://testing.lisaandroger.com/getperson.php?personID=I42032&tree=Johnhttp://genealogy.clanmoffat.org/getperson.php?personID=I19172&tree=UKEirehttp://www.bayanne.info/Shetland/getperson.php?personID=I49755&tree=bayanne_1Deaths and Burials in Walls 1838
March - Died John MOFFAT in Setter aged about 60 and was buried in Walls Church Yard.It cannot be proven that this John is my John but everything seems to fit. John & Lillias were living in Setter at least as late as 1823, because they had the following children:
1. Arthur MOFFAT, b. 1802, Breck, Sandness, SHI, SCT d. UNKNOWN
2. James MOFFAT, b. 1806, Seater, Walls, SHI, SCT d. 10 Feb 1863, Stove, Walls, SHI, SCT
3. Thomas MOFFAT, b. 1808, Setter, Walls, SHI, SCT d. 9 Jan 1887, Punds, Walls, SHI, SCT
4. Agnes MOFFAT, b. 1811, Setter, Walls, SHI, SCT d. 1811, Setter, Walls, SHI, SCT
5. Catherine MOFFAT, b. 1812, Setter, Walls, SHI, SCT d. 13 Sep 1874, Kellister, Sandness, SHI, SCT
6. Janet MOFFAT, b. 1817, Setter, Walls, SHI, SCT d. Bef 1847
7. William MOFFAT, b. 1820, Setter, Walls, SHI, SCT d. 18 Jan 1870, Brabister, Walls, SHI, SCT
8. Elizabeth MOFFAT, b. 1823, Setter, Walls, SHI, SCT d. 1889, Lerwick, SHI, SCT
Lillias is found living with the family of her son Thomas in Vadlure (Vadlin?) for the first census in 1841. She cannot be found in the 1851 or 1861 census', and a Lillias MOFFAT died 22 January 1864 in Brinister, Sandsting aged 83, which I can only assume is the same Lillias who was married in 1801.