Two possibilities born in the 1860's:
Robert Aitken Henderson born 14 June 1866 Linlithgow, West Lothian, Scotland. Father is Alexander Learmonth Henderson, mother is June Aitken.
Robert Aitken Henderson born 5 Feb 1861 Lochmaben, Dumfries, Scotland. Father is Thomas Henderson, mother is Helen Aitken.
Scotland Births and Baptisms, 1564-1950 Familysearch.org