I also have "Robertson" from Peterhead/ Grange.
My gr-gr- grandmother: Janet Robertson and her sister Jean both married
Their parents were William Robertson and Margaret McHattie ( married June
22,1798 Grange, Banff.
Six children that I know of:
Margaret: Mar 12,1799
Jean: Aug 29,1801 m: 1826 Peterhead to James Mitchell
Janet: Oct 6,1803 m: 1836 Peterhead to Thomas Mitchell
James: May 19,1806
Margaret: May 19,1806
William: Jan 16,1812
Love to hear from anyone who descends from this line.