I'd either not looked, or not found, Helen, dtr of James and Joan (FORSYTH) FAIRBAIRN in the 1841 census until now.
Whilst looking for something else, I happened across a proclamation for her marriage to Robert "SAFLAY" in the Peebleshire OPRs (Traquair) "Robert Saflay of the Parish of Melrose, Helen Fairbairn of this parish".
Having previously been satisfied that they had married in Melrose, I'd not looked further afield.
Spurred on by this find, I searched Peebleshire 1841 census, and found her as a female servant at Cardrona House (James & Elizabeth KER), supposedly along with an Isabella and Mary FAIRBAIRN as well, according to Ancestry transcriptions.
However, FreeCen says the latter are THORBURNs instead. There was an Isabella FORSYTH, not born county, with her though, possibly a cousin?