Many thanks Ruth, Anne and Ev.
I did find the 1901 Census data for M.J.Milne DUGUID, and like you, thought it the most likely. However, based on naming conventions of the time, I did expect to find the name "Duthie" (Eliza Jane 'Duthie') somewhere in my search.
Think I've found the Duthie connection
Mary Jane Milne m.
James Duguid in Old Machar in 1887 (as I mentioned previously). James Duguid was the son of
James Duguid, b. Old Meldrum abt. 1818, and
Jean/Jane Logan, b. Cruden in 1829 - James Duguid senior had a sister,
Martha Duguid (so she was James junior's aunt), who married
William Duthie, b. 1820 in St Cyrus - the Duthies were living in Peterculter around the time of Eliza Jane Duthie Duguid's birth. Martha Duthie (nee Duguid) died in 1899 in Peterculter, and her husband William died in 1903.
I've had a number of instances in my own tree where children have been named after the spouses of either a sibling or aunt/uncle - so looking sideways is always a good idea

No sign of a Lumsden yet though...
Ruth