Mary Bruce Duchess Richmond was born to Charles Bruce 4th Earl Elgin 3rd Earl Ailesbury and Caroline Campbell Countess Elgin and Ailesbury.
Before 1717 [her father] Charles Bruce 4th Earl Elgin 3rd Earl Ailesbury (age 34) and Anne Savile (age 25) were married. She the daughter of William Savile 2nd Marquess Halifax 1665-1700 and Elizabeth Grimston. He the son of Thomas Bruce 3rd Earl Elgin 2nd Earl Ailesbury (age 60) and Elizabeth Seymour Countess Elgin and Ailesbury 1655-1697.
In Jul 1717 [her father] Charles Bruce 4th Earl Elgin 3rd Earl Ailesbury (age 35) and Juliana Boyle (age 20) were married. She the daughter of Charles Boyle 2nd Earl Burlington and Juliana Noel Countess Burlington 1672-1750 (age 45). He the son of Thomas Bruce 3rd Earl Elgin 2nd Earl Ailesbury (age 61) and Elizabeth Seymour Countess Elgin and Ailesbury 1655-1697. They were second cousins.
In Mar 1739 [her father] Charles Bruce 4th Earl Elgin 3rd Earl Ailesbury (age 56) and [her mother] Caroline Campbell Countess Elgin and Ailesbury (age 18) were married. The difference in their ages was 38 years. She the daughter of John Campbell 4th Duke Argyll 1693-1770 (age 46) and Mary Drummond Bellenden. He the son of Thomas Bruce 3rd Earl Elgin 2nd Earl Ailesbury (age 83) and Elizabeth Seymour Countess Elgin and Ailesbury 1655-1697.
On 16 Dec 1741 [her grandfather] Thomas Bruce 3rd Earl Elgin 2nd Earl Ailesbury (age 85) died. His son [her father] Charles Bruce 4th Earl Elgin 3rd Earl Ailesbury (age 59) succeeded 4th Earl Elgin, 3rd Earl Ailesbury, 3rd Viscount Bruce of Ampthill in Bedfordshire. [her mother] Caroline Campbell Countess Elgin and Ailesbury (age 20) by marriage Countess Elgin, Countess Ailesbury.
In 1744 Henry Fox 1st Baron Holland (age 38) and [her future sister-in-law] Caroline Lennox 1st Baroness Holland (age 20) were married. She the daughter of Charles Lennox 2nd Duke Richmond (age 42) and Sarah Cadogan Duchess Richmond 1705-1751 (age 38). She a great granddaughter of King Charles II of England Scotland and Ireland. 
On 17 Apr 1746 [her father] Charles Bruce 4th Earl Elgin 3rd Earl Ailesbury (age 63) was created 1st Baron Bruce of Tottenham in Wiltshire with a special remainder to his nephew Thomas Brudenell 1st Earl Ailesbury (age 16).
On 10 Feb 1747 [her father] Charles Bruce 4th Earl Elgin 3rd Earl Ailesbury (age 64) died. Earl Ailesbury, Viscount Bruce of Ampthill in Bedfordshire, Baron Bruce of Skelton in Yorkshire, Baron Bruce of Whorlton in Yorkshire extinct.
Thomas Brudenell 1st Earl Ailesbury (age 17) succeeded 2nd Baron Bruce of Tottenham in Wiltshire.
Charles Bruce 9th Earl Kincardine 5th Earl Elgin 1732-1771 (age 14) succeeded 5th Earl Elgin.
On 19 Dec 1747 Field Marshal Henry Seymour-Conway (age 26) and [her mother] Caroline Campbell Countess Elgin and Ailesbury (age 26) were married. She the daughter of John Campbell 4th Duke Argyll 1693-1770 (age 54) and Mary Drummond Bellenden.
On 08 Aug 1750 Charles Lennox 2nd Duke Richmond (age 49) died. His son [her future husband] Charles Lennox 3rd Duke Richmond (age 15) succeeded 3rd Duke Richmond, 3rd Earl March, 3rd Baron Settrington.
On 01 Apr 1757 Charles Lennox 3rd Duke Richmond (age 22) and Mary Bruce Duchess Richmond were married. She by marriage Duchess Richmond. She the daughter of Charles Bruce 4th Earl Elgin 3rd Earl Ailesbury and Caroline Campbell Countess Elgin and Ailesbury (age 36). He the son of Charles Lennox 2nd Duke Richmond and Sarah Cadogan Duchess Richmond 1705-1751. He a great grandson of King Charles II of England Scotland and Ireland.
In 1758 Thomas Conolly (age 20) and [her sister-in-law] Louisa Augusta Lennox (age 14) were married. She the daughter of Charles Lennox 2nd Duke Richmond and Sarah Cadogan Duchess Richmond 1705-1751. She a great granddaughter of King Charles II of England Scotland and Ireland.
On 25 Dec 1759 [her brother-in-law] George Lennox (age 22) and Louisa Kerr were married. She the daughter of William Henry Kerr 4th Marquess Lothian 1710-1775 (age 49) and Caroline Darcy Marchioness Lothian. He the son of Charles Lennox 2nd Duke Richmond and Sarah Cadogan Duchess Richmond 1705-1751. He a great grandson of King Charles II of England Scotland and Ireland. She a great x 4 granddaughter of King James I of England and Ireland and VI of Scotland. 
On 04 May 1762 King George III of Great Britain and Ireland (age 23) created a number of new peerages ...
Edward Noel 1st Viscount Wentworth (age 46) was created 1st Viscount Wentworth.
William Courtenay 7th Earl Devon (age 53) was created 1st Viscount Courtenay.
Thomas Pelham Holles 1st Duke Newcastle-under-Lyme (age 68) was created 1st Baron Pelham of Stanmer in Sussex with default to his cousin Thomas Pelham (age 34).
[her sister-in-law] Caroline Lennox 1st Baroness Holland (age 39) was created 1st Baron Holland in Lincolnshire. Henry Fox 1st Baron Holland (age 56) by marriage Baron Holland in Lincolnshire.
John Perceval 2nd Earl Egmont (age 51) was created 1st Baron Lovel and Holland of Enmore in Somerset.
John Montagu 1st Baron Montagu (age 27) was created 1st Baron Montagu of Boughton in Northamptonshire.
Joseph Damer 1st Earl Dorchester (age 44) was created 1st Baron Milton of Milton Abbey in Dorset.
Edward Hussey-Montagu 1st Earl Beaulieu (age 41) was created 1st Baron Beaulieu of Beaulieu in Hampshire with a special remainder to his heirs male with his current wife Isabella Montagu Duchess Manchester (age 56).
On 12 May 1762 George Venables-Vernon 1st Baron Vernon (age 53) was created 1st Baron Vernon of Kinderton in Cheshire. Martha Harcourt Baroness Vernon of Kinderton (age 46) by marriage Baroness Vernon of Kinderton in Cheshire.
George Fox Lane 1st Baron Bingley (age 65) was created 1st Baron Bingley. Harriet Benson Baroness Bingley (age 57) by marriage Baroness Bingley.
On 02 Jun 1762 Thomas Charles Bunbury 6th Baronet (age 22) and [her sister-in-law] Sarah Lennox Lady Bunbury (age 17) were married. The marriage was dissolved in Feb 1769 since she had had a child with William Gordon (age 18) in 1768. The decree for divorce was issued on 14 May 1776. One of her daughters with Colonel George Napier (age 11), Emily Louisa Augusta Napier Lady Bunbury, would subsequently marry Charles Bunbury's nephew and heir Henry Edward Bunbury 7th Baronet. She the daughter of Charles Lennox 2nd Duke Richmond and Sarah Cadogan Duchess Richmond 1705-1751. She a great granddaughter of King Charles II of England Scotland and Ireland.
On 21 Nov 1769 [her sister-in-law] Cecilia Lennox (age 19) died.
On 24 Jul 1774 [her sister-in-law] Caroline Lennox 1st Baroness Holland (age 51) died. Her son Stephen Fox 2nd Baron Holland (age 29) succeeded 2nd Baron Holland in Lincolnshire.
On 27 Aug 1781 Colonel George Napier (age 30) and [her sister-in-law] Sarah Lennox Lady Bunbury (age 36) were married. She the daughter of Charles Lennox 2nd Duke Richmond and Sarah Cadogan Duchess Richmond 1705-1751. She a great granddaughter of King Charles II of England Scotland and Ireland.
On 05 Nov 1796 Mary Bruce Duchess Richmond died.
On 29 Dec 1806 [her former husband] Charles Lennox 3rd Duke Richmond (age 71) died at Goodwood West Sussex. He was buried at Chichester Cathedral [Map]. His nephew Charles Lennox 4th Duke Richmond (age 42) succeeded 4th Duke Richmond, 4th Earl March, 4th Baron Settrington. Charlotte Gordon Duchess Richmond 1768-1842 (age 38) by marriage Duchess Richmond.
Paternal Family Tree: Bruce of Elgin
Maternal Family Tree: Elizabeth Vernon Countess Southampton 1572-1655
Kings Wessex: Great x 21 Grand Daughter of King Edmund "Ironside" I of England
Kings Gwynedd: Great x 18 Grand Daughter of Owain "Great" King Gwynedd 1100-1170
Kings Seisyllwg: Great x 23 Grand Daughter of Hywel "Dda aka Good" King Seisyllwg King Deheubarth
Kings Powys: Great x 18 Grand Daughter of Maredudd ap Bleddyn King Powys 1047-1132
Kings England: Great x 7 Grand Daughter of King Henry VII of England and Ireland
Kings Scotland: Great x 14 Grand Daughter of Robert "The Bruce" I King Scotland
Kings Franks: Great x 17 Grand Daughter of Louis VII King Franks
Kings France: Great x 10 Grand Daughter of Charles "Beloved Mad" VI King France
Great x 4 Grandfather: Edward Bruce
Great x 3 Grandfather: Edward Bruce 1st Lord Kinloss
Great x 2 Grandfather: Thomas Bruce 1st Earl Elgin
Great x 1 Grandfather: Robert Bruce 2nd Earl Elgin 1st Earl Ailesbury 9 x Great Grand Son of King Edward III of England
Great x 4 Grandfather: John Chichester
6 x Great Grand Son of King Edward III of England
Great x 3 Grandfather: Robert Chichester 7 x Great Grand Son of King Edward III of England
Great x 4 Grandmother: Anne Denys 6 x Great Grand Daughter of King Edward III of England
Great x 2 Grandmother: Anne Chichester 8 x Great Grand Daughter of King Edward III of England
Great x 4 Grandfather: John Harington 1st Baron Harington
Great x 3 Grandmother: Frances Harrington
Great x 4 Grandmother: Anne Keilway Baroness Harington
GrandFather: Thomas Bruce 3rd Earl Elgin 2nd Earl Ailesbury 10 x Great Grand Son of King Edward III of England
Father: Charles Bruce 4th Earl Elgin 3rd Earl Ailesbury 6 x Great Grand Son of King Henry VII of England and Ireland
Great x 4 Grandfather: Edward Seymour 1st Earl Hertford 5 x Great Grand Son of King Edward III of England
Great x 3 Grandfather: Edward Seymour 2 x Great Grand Son of King Henry VII of England and Ireland
Great x 4 Grandmother: Catherine Grey Countess Hertford
Great Grand Daughter of King Henry VII of England and Ireland
Great x 2 Grandfather: William Seymour 2nd Duke Somerset 3 x Great Grand Son of King Henry VII of England and Ireland
Great x 3 Grandmother: Honora Rogers
Great x 1 Grandfather: Henry Seymour 4 x Great Grand Son of King Henry VII of England and Ireland
Great x 4 Grandfather: Walter Devereux 1st Earl Essex
6 x Great Grand Son of King Edward III of England
Great x 3 Grandfather: Robert Devereux 2nd Earl Essex 7 x Great Grand Son of King Edward III of England
Great x 4 Grandmother: Lettice Knollys Countess Essex
6 x Great Grand Daughter of King Edward III of England
Great x 2 Grandmother: Frances Devereux Duchess of Somerset 8 x Great Grand Daughter of King Edward III of England
Great x 4 Grandfather: Francis Walsingham 8 x Great Grand Son of King Edward "Longshanks" I of England
Great x 3 Grandmother: Frances Walsingham Countess Essex 9 x Great Grand Daughter of King Edward "Longshanks" I of England
Great x 4 Grandmother: Ursula St Barbe
GrandMother: Elizabeth Seymour Countess Elgin and Ailesbury 1655-1697 5 x Great Grand Daughter of King Henry VII of England and Ireland
Great x 4 Grandfather: Arthur Capell 6 x Great Grand Son of King Edward III of England
Great x 3 Grandfather: Henry Capell 7 x Great Grand Son of King Edward III of England
Great x 4 Grandmother: Margaret Grey 6 x Great Grand Daughter of King Edward III of England
Great x 2 Grandfather: Arthur Capell 1st Baron Capell Hadham 8 x Great Grand Son of King Edward III of England
Great x 4 Grandfather: Edward Montagu 8 x Great Grand Son of King Edward "Longshanks" I of England
Great x 3 Grandmother: Theodosia Montagu 9 x Great Grand Daughter of King Edward "Longshanks" I of England
Great x 4 Grandmother: Elizabeth Harrington
Great x 1 Grandmother: Mary Capell Duchess Beaufort 9 x Great Grand Daughter of King Edward III of England
Great x 4 Grandfather: Charles Morrison
6 x Great Grand Son of King Edward III of England
Great x 3 Grandfather: Charles Morrison 7 x Great Grand Son of King Edward III of England
Great x 4 Grandmother: Dorothea Clerke
Great x 2 Grandmother: Elizabeth Morrison Baroness Capell Hadham 8 x Great Grand Daughter of King Edward III of England
Great x 4 Grandfather: Baptist Hicks 1st Viscount Campden
Great x 3 Grandmother: Mary Hicks Lady Cooper
Great x 4 Grandmother: Elizabeth May Viscountess Campden
Mary Bruce Duchess Richmond -1796 7 x Great Grand Daughter of King Henry VII of England and Ireland
Great x 4 Grandfather: Archibald Campbell 7th Earl Argyll 7 x Great Grand Son of King Edward III of England
Great x 3 Grandfather: Archibald Campbell 1st Marquess Argyll 8 x Great Grand Son of King Edward III of England
Great x 4 Grandmother: Agnes Douglas Countess Argyll 1574-1607 12 x Great Grand Daughter of King John "Lackland" of England
Great x 2 Grandfather: Archibald Campbell 9th Earl Argyll 9 x Great Grand Son of King Edward III of England
Great x 4 Grandfather: William Douglas 7th Earl Morton 1582-1648 8 x Great Grand Son of King Edward III of England
Great x 3 Grandmother: Margaret Douglas Marchioness Argyll 1610-1678 9 x Great Grand Daughter of King Edward III of England
Great x 4 Grandmother: Anne Keith Countess Morton 8 x Great Grand Daughter of King Edward III of England
Great x 1 Grandfather: John Campbell 6 x Great Grand Son of King Henry VII of England and Ireland
Great x 4 Grandfather: James Stewart 3rd Earl Moray 1590-1638
3 x Great Grand Son of King Henry VII of England and Ireland
Great x 3 Grandfather: James Stewart 4th Earl Moray 1611-1653 4 x Great Grand Son of King Henry VII of England and Ireland
Great x 4 Grandmother: Anne Gordon Countess Moray 7 x Great Grand Daughter of King Edward III of England
Great x 2 Grandmother: Mary Stewart Countess Argyll 1628-1668 5 x Great Grand Daughter of King Henry VII of England and Ireland
Great x 4 Grandfather: Alexander Home 1st Earl of Home 1566-1619
Great x 3 Grandmother: Margaret Home Countess Moray 8 x Great Grand Daughter of King Edward III of England
Great x 4 Grandmother: Mary Dudley Countess Home
7 x Great Grand Daughter of King Edward III of England
GrandFather: John Campbell 4th Duke Argyll 1693-1770 7 x Great Grand Son of King Henry VII of England and Ireland
Great x 4 Grandfather: James Elphinstone of Barnes 13 x Great Grand Son of King John "Lackland" of England
Great x 3 Grandfather: Alexander Elphinstone 6th Lord Elphinstone 14 x Great Grand Son of King John "Lackland" of England
Great x 2 Grandfather: John Elphinstone 8th Lord Elphinstone 15 x Great Grand Son of King John "Lackland" of England
Great x 1 Grandmother: Elizabeth Elphinstone 16 x Great Grand Daughter of King John "Lackland" of England
Mother: Caroline Campbell Countess Elgin and Ailesbury 8 x Great Grand Daughter of King Henry VII of England and Ireland
Great x 4 Grandfather: Patrick Drummond 3rd Lord Drummond
Great x 3 Grandfather: John Drummond 2nd Earl Perth 1588-1662
Great x 2 Grandfather: William Ker 2nd Earl Roxburghe 1623-1675 8 x Great Grand Son of King Edward III of England
Great x 4 Grandfather: Robert Ker 1st Earl Roxburghe 1570-1650 13 x Great Grand Son of King John "Lackland" of England
Great x 3 Grandmother: Jean Ker Countess Perth 7 x Great Grand Daughter of King Edward III of England
Great x 4 Grandmother: Margaret Maitland 6 x Great Grand Daughter of King Edward III of England
Great x 1 Grandfather: John Bellenden 9 x Great Grand Son of King Edward III of England
Great x 4 Grandfather: Robert Ker 1st Earl Roxburghe 1570-1650 13 x Great Grand Son of King John "Lackland" of England
Great x 3 Grandfather: Henry Ker 14 x Great Grand Son of King John "Lackland" of England
Great x 4 Grandmother: Jean Drummond Countess Roxburghe 1585-1643
Great x 2 Grandmother: Jane Ker Countess Roxburgh -1675 9 x Great Grand Daughter of King Edward III of England
Great x 4 Grandfather: William Hay 10th Earl Erroll 1596-1636
7 x Great Grand Son of King Edward III of England
Great x 3 Grandmother: Margaret Hay Countess Cassilis -1695 8 x Great Grand Daughter of King Edward III of England
Great x 4 Grandmother: Anne Lyon Countess Erroll -1637 8 x Great Grand Daughter of King Edward III of England
GrandMother: Mary Drummond Bellenden 10 x Great Grand Daughter of King Edward III of England
Great x 4 Grandfather: Garret Moore 1st Viscount Moore of Drogheda
Great x 3 Grandfather: Charles Moore 2nd Viscount Moore of Drogheda
Great x 4 Grandmother: Mary Colley Viscountess Moore and Wilmot
Great x 2 Grandfather: Henry Moore 1st Earl Drogheda 1622-1676
Great x 4 Grandfather: Adam Loftus 1st Viscount Loftus
Great x 3 Grandmother: Alice Loftus Viscountess Moore
Great x 1 Grandmother: Mary Moore 9 x Great Grand Daughter of Henry IV King England
Great x 4 Grandfather: Robert Spencer 1st Baron Spencer
Great x 3 Grandfather: William Spencer 2nd Baron Spencer 8 x Great Grand Son of King Edward III of England
Great x 4 Grandmother: Margaret Willoughby
7 x Great Grand Daughter of King Edward III of England
Great x 2 Grandmother: Alice Spencer Countess Drogheda 1625-1696 8 x Great Grand Daughter of Henry IV King England
Great x 4 Grandfather: Henry Wriothesley 3rd Earl of Southampton
7 x Great Grand Son of King Edward III of England
Great x 3 Grandmother: Penelope Wriothesley Baroness Spencer Wormleighton 7 x Great Grand Daughter of Henry IV King England
Great x 4 Grandmother: Elizabeth Vernon Countess Southampton 1572-1655 6 x Great Grand Daughter of Henry IV King England