Two more have given an opinion and have agreed to Jairdain.
I have found a baptism at Dalkeith 25.11.1770 of a James Jerdain born the 21.11.1770 son of Wiliam Jerdain and Jean Gourley.  What do you think?  Married to Elisabeth Thomson.  5 children Margaret  Jairdain 13.091807, Marion Jardain 06.08.1809,  Elisabeth Jairdane 29.11.1811, John Thompson Jairdain 25.12.1814, James Jairdain 19.12.1816 all at Dalkeith. There is an 1851 census of a James Jardine born circa 1769 aged 82 in Midlothian. 
Also having children around the same time was an Alexander Storie with a wife Elizabeth Jarden/Jardine etc.  South Leith Midlothian.  Helen Bolton's mother was called Elisabeth Storrie/Storie/Storey/Story?
On John McPherson I have found one that was having children at the same time.  Married to Catherine Taylor at Cannongate  03.08.1798.  James 23.03.1801, Paul 17.07.1803, John 15.04.1806
That's all I have found so far