I am sorry to say we don't seem to have a match here unless your James MACGREGOR, son of Gx3 Grandfather emigrated just prior to 1867 or later but we are in the right area. Since I posted my first message I have obtained my Alexander MacGregor's death certificate, he was b. 1867-d. 1939. His death certificate gives the father as James MACGREGOR, shepherd. Too late for your James MACGREGOR 1779-1862 but his son James could be possible, if he was in the area prior to 1867.
My problem is I can't find Alexander MACGREGOR junior between his birth and his marriage.
I think he may have been in Glasgow as several appear on the 1891 Census, but I have not yet indulged in viewing the images on-line. He definitely returned to the area to marry a Jessie Tolmie 1895 in Newtonmore; moving back to Glasgow where they had their first child Helen and then back up North where two further children, Isabella and Jessie, were born in Kingussie. According to the 1901 Census he was working on his own account as a Carpenter from his home "Rowanlea" in Newtonmore, where he also died in 1939. There is no marriage to be found for Alexander's parents, Ann WINCHESTER & James MACGREGOR and I am still not sure if this James MACGREGOR, given as father of Alexander, died or just did not marry the mother. Alexander was born in Inverness and his mother subsequently married there, twice. I think I really need to check the 1871 Census for them.
I will be looking for his marriage certificate when I am next back in Scotland so do lets keep in touch in case I turn up anything else. I have been unable to find him in the burial registers for the area, at least the ones under the care of the Highland Council but I hope to check out Laggan Church on the next visit, probably in early summer this year.
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for most of the year.