Daughter of David Laing Montgomerie (d. 1752)1 and Veronica Boswell (d. 1742), and as such a first cousin of James Boswell. Sister of Margaret, who married James Boswell in 1769.
She succeeded to the Lainshaw estate following the death of her older brother James in 1767.
Elizabeth married firstly Alexander Montgomerie-Cuninghame of Kirktonholme (d. 1770), with whom she had at least five children, including:
- Sir Walter Montgomerie Cuninghame (d. 1814), who in 1770 succeeded his paternal grandfather as 4th Baronet of Corsehill, and who later assumed the title of Lord Lyle, although this remained unacknowledged by his peers and the authorities. In 1779, he sold the estate of Lainshaw to his relative William Cuninghame of Bridgehouse.
- Sir David Cuninghame, who succeeded his brother as 5th Baronet of Corsehill.
- Sir James Cuninghame, 6th Baronet of Corsehill, and father of the 7th and 8th Baronets
She married secondly Charles Beaumont, who according to one source was "a speculator in some coal works, and upon whom she made large settlements, though the estate had already been much encumbered previous to the death of her brother James."2
Her exact date of death is not known, but it must have been between 1770, when her first husband died and she married Charles Beaumont, and 1779, when the Lainshaw estate was sold by her oldest son.