Hi Chris,
The four Hogg children according to Familysearch are all christened in  North Leith, Midlothian
There is a couple on the 1841 Census at Spenses Place, Leith South
William Hogg   age 50   Joiner Journeyman     born outside Census County
Catharine Hogg  age 45                                 born outside Census County
Spellings above as per Freecen transcription.
The 1841 Census advised people to round down their ages to nearest 0 or 5 - although in my experience some folk rounded up too! And according to this Census these people were not Midlothian born.
Don't know if this is your couple but worth looking at.
Looby 
