Hi Tanya,
James Robertson died 1874, age 76 at St Andrews Llanbryd (Moray) Ref: 142/9
Source: Scotland's People.
https://www.scotlandspeople.gov.uk/
Question for you: There is a 14 year old Alexander Robertson living with Jean's parents Charles and Jane Phyn at St Andrews Llanbryd (Moray), Haddingtonshire (East Lothian) on the 1841 Census, have you come across Alexander before?
"Scotland Census, 1841," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:VYC7-YFK : 10 July 2019), Charles Phyn, St Andrews Llanbryd (Moray), Haddingtonshire (East Lothian), Scotland; from "1841 England, Scotland & Wales census," database, findmypast (http://www.findmypast.com : 2012); citing p. 7, PRO HO 107, New Register House, Edinburgh; FHL microfilm 1,042,645.
On the 1871 Census James Robertson is living with his daughter Jane Ross and family at Walkers Crescent, 10, St Andrews Thanbryde, St Andrews Lhanbryd, Moray. On census night of 1871 Jane's husband Alexander Ross, a 38 year old Farm Servant born at Knockando, was at Stone Cross Hill, St Andrews Thanbryde, St Andrews Lhanbryd.
Alexander Ross married Jane Robertson on 27 Aug 1853 at St Andrews, Lhanbryd, Moray.
In Scotland, and elsewhere many names are interchangeable often in ways which may and do confuse, - Jessie, Janet, Jane and Jean are a good example of interchangeable names.
http://www.whatsinaname.net/female-names/Jessie.html
Source: Find My Past.
I shall continue to look for more information tomorrow......
James Robertson and Jean Phyn's daughter Margaret:
Margaret Robertson married John Peterkin on 11 April 1846 at St Andrews-Lhanbryd,Moray.
Margaret Peterkin died 24 June 1894, age 72 at St Andrews Llanbryd (Moray) Ref: 142/ 6 (Scotlands People)
1851 Census: The Peterkin family were at Llanbryde, St Andrews Lhanbryde, Lhanbryde Village, Moray.
A Jane Robertson, age 17, born about 1834 at Urquhart was a House Servant at the Peterkin residence.
John Peterkin:
http://libindx.moray.gov.uk/subjects/subject_people_report_view.asp?REF_ID=NM138414
Margaret Robertson Peterkin:
http://libindx.moray.gov.uk/subjects/subject_people_report_view.asp?REF_ID=NM138435
More to follow...........
Jean Phyn Robertson's Parents:
Charles Phyn/Finn (c. 1762 to 02 MAR 1845)
http://libindx.moray.gov.uk/subjects/subject_people_report_view.asp?REF_ID=NM068607
Jean Todd Phyn/Finn (06 OCT 1773 to 15 FEB 1859)
http://libindx.moray.gov.uk/subjects/subject_people_report_view.asp?REF_ID=NM139047