To Rory, Juli, Neil, Toni, and all others interested--
I do not believe that ALL Argyll Sinclairs were originally McNokairds. However, I do believe the great majority were! According to several sources, Sinclairs in the Western Isles and Hebrides were McNokairds as well. Neil quoted Arthur Binning as having read a source that listed Sinclairs in the Cowal penninsula (Neil's family came from here) as "strangers." Arthur said that this meant they had come from elsewhere to work the land in response to advertisments.
Now, Neil, I get the feeling that you believe some northern Sinclairs settled in Argyll before the 17th century and became known as McNokairds. Thereupon, you believe they changed their surname back to Sinclair in the first half of the 18th century. Did I understand that correctly?
I do not believe this is the case--Black cites many specific sources for McNokairds going back centuries. Let me quote his citations:
Gregor Makenkerd agreed to serve Edward I of England in France, 1297 (Bain II, p. 242)
Iain Mc nocerdych was charter witness in Lismore, 1525 (HP, IV, p. 27)
Gillecreist M'Conoquhy Duy VcNocarde in record in Argyll, 1574 (OPS II, p. 127)
Gillecreist Mckonchy Duff V'Nokerd, native servant to Campbell of Glenurchy, 1580 (BBT, p. 223)
John M'Nocaird was tenant in Eyick, 1594 (ibid, p. 283)
Archibald M'Nokaird was portioner of Drumurk, 1629 (Sasines, 286)
Myldoniche or Moldonyt McNoheardie or McNokeardie in Carnakalliche was put to the horn, 1629 (RPC...)
Patrick Dow M'Nokerd in Auchinchalden and Angus M'Nokerd in Braklead appear in 1638 (BBT, p. 403)
Finlay Mcnakaird was an 'engager' on the royalist side from Urquhart, 1649 (IDR, p. 368)
Duncan M'Knokaird is in Monienrinach, 1672 (HP II, p. 208)
John Dow M'Nockard and Malcolm M'Nokard in Kilvicewn, and Duncan M'Nocard in Scur were denounced rebels, 1675 (HP I)
Archibald M'Nokaird was merchant burgess in Inveraray, 1695 (Campbell I, p. 13)
Dond. McNougard is recorded in Gerrich, Islay, 1741 (Bk. Isley, p. 559)
Black finishes his article with the statement, "In Argyllshire the name is now rendered Sinclair." This is what got me started! I had to find out and prove, if I could, Black's statement. I was able to do that, and Juli is daily finding even more proof in the parish registers!
In addition to Black's Surnames above, I added Duncan C. McTavish's The Commons of Argyll (Lochgilphead: James S. Annan, 1935) which contains lists of men in Argyll in 1685 and 1692. McNokairds abound! Only two Sinclairs were found--and they lived next to two McNokairds. Thus, this time period can be used as a "starting point" for when the name change possibly began. Parish registers in Inveraray are extant from this time period, with certain gaps, but other parishes such as Glenorchy and those in Islay were not extant until much later.
Also, Toni Sinclair has added the McNokairds found in Isle of Islay in 1730s and 1741, as set forth in Freda Ramsay's The Day Book of Daniel Campbell of Shawfield 1767 (Aberdeen University Press).
I trust these lists and registers because they are absolutes--not someone's opinion or theory. They were taken at a certain time period and set forth "as it was," so to speak. They are presumably unaltered and unadulterated. Through use of these lists and registers, I was able to draw my own conjectures!
I hope I haven't bored you all out there--just keeping the discussion going!