This looks very promising. Robert Livingstone is 20 years older than Agnes. But, possible ... and very tempting to put two and two together. Do the ages of this family tie in with the ages of your family Bruce?
The next thing to do would be to search for these people in 1851 to see if they are still around ...
Sancti, would you recommend that Bruce buy some credits from Scotland's People to see this census image? I am not familiar with the Scottish censuses (apart from the index on Ancestry) but presume the 1841 does not tell us much.
I actually found these Glassford entries many months ago (downloaded with credits from Scotland's People as you suggest) but discounted them because the Agnes (who should be Agnes Craig born in the 1790s and married in 1813) is listed as age 35 which puts the birth at 1806 - even 1802 if there is some rounding. That doesn't seem right - married at age 11. The ages for James (49) and Alexander (13 I think it says) are close and Agnes Jr 20 is close too.
There are so many women named Agnes (I call them Agnii) too that I automatically presume it is just another incorrect Agnes Cumming.
However, it does all sound interesting upon further reflection. Robert Livingston age 40 - who knows? Looking at the Livingston YDNA project at FTDNA it is interesting that "McLea" is included as a variation. The Cathkin farm owner was Walter Ewing McLae. All quite suspicious.
If the census age of mother Agnes was just a mistake (or vanity - wanting to appear younger?) then this could be a good fit. However I wonder about the other children such as Ann (1825-1895) and another Robert (1829-?) and why they weren't there.
Thank you and @sancti for the good sleuth work.
Terry