Benny Gillies - yes, was well aware of Robert's given parents but if the 'Joseph' aged 4 g/grandson found by Looby was actually your Robert was trying to see if the George Gillies 8, also a g/grandson, was also a son of Joseph Gillies, Ploughman and to see who was given as his mother, i.e. was she also named Ann Asher, or was it possibly slightly different such as different first name or different surname. The only occasion when Robert's parents are given are at his marriage - when he died aged 91 in 1945 the informant clearly didn't know these details as his parents details are blank.
Joseph Gillies are thin on the ground as has been found and to now know that Georges' father was also a Joseph Gillies, Ploughman (deceased) seemed to much of a coincidence to ignore. Plus the 4 year old Joseph in 1861 effectively 'disappears' at the time when Robert first appears by this name in census in 1871.
Forfarian - I noticed at the outset that Robert would only have been 17 at marriage (not 19) but his age in 1871 was 14, 1881 24, 1891 34, 1901 45 so he was pretty consistent with a circa birthdate of 1857 hence the 4 year old 'Joseph' in 1861 looking a strong possibility for him.
Clearly, working 'inside the box' from given facts is not panning out so one then has to start looking 'outside the box' so to speak.
What we now know is that Robert's father was a Joseph Gillies, ploughman, George (bc.1853) was also a son of a Joseph Gillies, ploughman, the only likely candidate for such Joseph died in 1858 (single), son of a James (son of William), and that in 1861 living with William the household includes 2 g/grandsons i.e. George 8 and Joseph (later Robert?) 4, who are both known to be sons of Joseph Gillies, ploughman.
Phew, hope I've explained that clearly enough.
Annette