Note - this biography probably relies too much on the Wikipedia article for this person and needs to be amended.
Lady Emilia Mary Lennox was born 6 October 1731 and baptised at St. George's, Hanover Square, London. She was the daughter of Charles Lennox, 2nd Duke of Richmond, and Lady Sarah Cadogan. Emilia, one of the famous Lennox Sisters, was descended from King Charles II and was therefore a distant fifth cousin of King George III. Both Emilia and her husband, James, were descended from King James VI and I. She was also a goddaughter of King George II.
On 7 February 1747 at Whitehall Place, Londan in St. Margaret's, Lady Emilia (at the age of 15) married the immensely wealthy James FitzGerald, 20th Earl of Kildare, son of Robert FitzGerald, 19th Earl of Kildare, and Lady Mary O'Brien. They went on to live in Ireland, firstly at Leinster House and then at Carton House.
The marriage between Emily and James was a happy one, despite Lord Kildare's constant infidelities. The couple had nineteen children:
George FitzGerald, Earl of Offaly (15 January 1748 - Richmond House, 26 September 1765)
William FitzGerald, 2nd Duke of Leinster (Arlington Place, Piccadilly, London, 12 March 1749 - Carton House, Kildare, 20 October 1804).
Lady Caroline FitzGerald (1750 – 1754).
Lady Emily Mary FitzGerald (15 March 1751 – 8 April 1818), married Charles Coote, Baron Coote of Coolony and Earl of Bellamont. The couple had five children, one son who died young (b1776) and four daughters. Emily died in Penzance, Cornwall in 1818 after a lingering illness.
Lady Henrietta FitzGerald (1753 – 1763).
Lady Caroline FitzGerald (born and died 1755).
Charles FitzGerald, 1st Baron Lecale (30 June 1756 - 30 June 1810).
Lady Charlotte Mary Gertrude FitzGerald (29 May 1758 – 13 September 1836), married Joseph Strutt and was made first Baroness Rayleigh. Had issue.
Lady Louisa Bridget FitzGerald (1760 – 1765).
Lord Henry FitzGerald (30 July 1761 - 8 July 1829), general; married Charlotte Boyle and had issue, who take by inheritance the surname "de Ros".
Lady Sophia Sarah Mary FitzGerald (1762 – 21 March 1845).
Lord Edward FitzGerald (15 October 1763 – 4 June 1798).
Lord Robert Stephen FitzGerald (1765 - 2 January 1833), a diplomat; married Sophia Charlotte Fielding and had issue.
Lord Gerald FitzGerald (January 1766 – 1788). Drowned, went down with the ship in which he was serving.
Lord Augustus FitzGerald (1767 – 1771).
Lady Fanny FitzGerald (1770 – 1775).
Lady Lucy Anne FitzGerald (1771 – 1851), who took part in the Irish Rebellion of 1798. She was married to Admiral Sir Thomas Foley, who served with distinction under Lord Nelson. They had no children.
Lady Louisa FitzGerald (1772 – 1776).
Lord George Simon FitzGerald (16 April 1773 – 1783). Recognized as son of Lord Kildare, but in fact was the biological son of his brother's tutor, William Ogilvie, Lady Emily's lover.
Her husband, James, died, aged only fifty-one, on 19 November 1773 at Leinster House, Dublin. Requiring a tutor for her young children, Lady Emelia employed William Ogilvie, an uncouth Scot nine years younger than herself. He had been employed as an usher for £12 a year at a very small school in Ireland and was fortunate to be recommended to her. The Dowager Duchess then not only conceived a passion for him but also created a minor sensation when she married him in 1774, producing three more daughters. Even so, she continued to be known as The Dowager Duchess of Leinster.
Emilia died, aged eighty-two, on 27 March 1814 in Grosvenor Square, London. William Ogilvie died 18 November 1832 at Ardglass, county Down.