He was the Laird of the Holm of Dalquairn & Glencrosh, and a JP.
Lineage (from Burke's Landed Gentry):
— Mr. John McMillan is the lineal descendant and representative of the ancient family of McMillan of Brockloch and Holm of Dalquhairn, in the parish of Carsphairn, co. Kirkcudbright. The lands of Brockloch were held originally by the tenure called "Manrent," but when King Robert the Bruce created the Chief of Brockloch Baron of Ken, he obtained a charter of all his lands, 'blanche' of
the Crown. The properties of Brockloch and Holm of Dalquhairn were united through a marriage in 1741, but on the death of John McMillan in 1852, Brockloch passed from the possession of the MacMillans, but Holm of Dalquhairn, which comprises Upper and Nether Holm and Clenoch, is still the property of the representative of the family.
John MacMillan, younger, of Holm married Margaret
Thompson, eldest daughter of Thomas Moffat, Esq., J.P., of
Ardnacloich, County of Dumfries, and had issue :—
Robert of Holm.
Thomas Moffat.
John James.
Margaret Robina.
Mary Goldie.
Source: Clan Macmillan by Somerled Macmillan
Clan MacMillan crest: Miseris succerere disco (I learn to succour the unfortunate)
"Glencrosh continued in the possession of the Gibsons until
about 1870, when the estate was sold to John M'Millan of
Holm, in whose family it continues."
"A Glencairn Ploughing Society has existed since 1869.
The Society was instituted, for the encouragement of ploughing,
at a meeting held in Dumfries on the 27th day of January, when
John M'Millan of Glencrosh was appointed President and Robert
W. Sloane Secretary."
pg 171, 'Glencairn, The Annals of an Inland Parish' by John Corrie, 1910
1871 census, Glencrosh, Glencairn:
John Mcmillan 38
Margaret Mcmillan 34
Margaret Mcmillan 7
Robert Mcmillan 5
Thomas Mcmillan 3
John James Mcmillan 2
Barbara Campbell 40
Agness Armstrong 17
Margaret Todd 26
Margaret Fergusson 26
Isabella Beattie 17
John Brown 27
1881 census, Glencrosh, Glencairn:
John McMillan 48
Margaret McMillan 45
Robert McMillan 15
John James McMillan 12
David Jackson McMillan 8
Mary Goldie McMillan 6
Jane Haining 28
Agnes Armstrong 27
Mary McAdam 19
Jane Armstrong 24
Archie McAdam 17
1891 census, Glencrosh:
John McMillan 58
Margaret T McMillan 55
Margaret R McMillan 27
Robert McMillan 25
Thomas McMillan 23
John J McMillan 22
Mary G McMillan 16
Christina K Malcolm 30
Isabella Hyslop 38
Elizabeth Lawson 20
Margaret Lauder 23
Martha Brown 14
John Andeson 20
Thomas Topping 19
David Hastings 17
James McAdam 14
Gravestone Inscription at Carsphairn Parish Church:
IN LOVING MEMORY
OF
JOHN McMILLAN
OF GLENCROSH & HOLM
WHO DIED 10TH DECEMBER 1895
AGED 82 YEARS
ALSO OF
MARGARET THOMPSON MOFFAT
HIS WIFE
WHO DIED AT GLENCROSH 3RD MARCH 1900
AGED 65 YEARS
Picture via:
Celtic Monthly Magazine
https://archive.org/texts/flipbook/flippy.php?id=celticmonthlymag01mack http://digital.nls.uk/early-gaelic-book-collections/pageturner.cfm?id=75846265&mode=transcription Ref:
Bernard Burke. A genealogical and heraldic history of the landed gentry of Great Britain & Ireland (Volume 2)
http://www.ebooksread.com/authors-eng/bernard-burke/a-genealogical-and-heraldic-history-of-the-landed-gentry-of-great-britain--irel-kru/page-58-a-genealogical-and-heraldic-history-of-the-landed-gentry-of-great-britain--irel-kru.shtml 
