William John Cavendish-Scott-Bentinck 5th Duke Portland was elected MP King's Lynn following the death of his brother who had previously held the seat.
On 04 Aug 1795 [his father] William Henry Cavendish-Scott-Bentinck 4th Duke Portland 1768-1854 (age 27) and [his mother] (age 21) were married. She by marriage Duchess Portland. He the son of William Cavendish-Bentinck 3rd Duke Portland (age 57) and Dorothy Cavendish 3rd Duchess Portland 1750-1794.
On 17 Sep 1800 William John Cavendish-Scott-Bentinck 5th Duke Portland was born to William Henry Cavendish-Scott-Bentinck 4th Duke Portland 1768-1854 (age 32) and (age 26). The date somewhat uncertain according to different sources; Cracroft says 12 Sep 1808 which may be the date he was baptised and 1808 a typo? He was known as John since all the male members of the family were given the first name John.
On 30 Sep 1800 William John Cavendish-Scott-Bentinck 5th Duke Portland was baptised at St George's Church, Hanover Square.
On 30 Oct 1809 [his grandfather] William Cavendish-Bentinck 3rd Duke Portland (age 71) died. His son [his father] William Henry Cavendish-Scott-Bentinck 4th Duke Portland 1768-1854 (age 41) succeeded 4th Duke Portland, 5th Earl of Portland.
On 27 Mar 1854 [his father] William Henry Cavendish-Scott-Bentinck 4th Duke Portland 1768-1854 (age 85) died. His son William John Cavendish-Scott-Bentinck 5th Duke Portland (age 53) succeeded 5th Duke Portland, 6th Earl of Portland although it took him three years before he took his seat in the House of Lords.
On 06 Dec 1879 William John Cavendish-Scott-Bentinck 5th Duke Portland (age 79) died unmarried at his London residence Harcourt House Cavendish Square Marylebone. He was buried in Kensal Green Cemetery. His first cousin once removed William Cavendish-Bentinck 6th Duke Portland (age 21) succeeded 6th Duke Portland, 7th Earl of Portland.
Paternal Family Tree: Bentinck
Kings Wessex: Great x 23 Grand Son of King Edmund "Ironside" I of England
Kings Gwynedd: Great x 19 Grand Son of Owain "Great" King Gwynedd 1100-1170
Kings Seisyllwg: Great x 25 Grand Son of Hywel "Dda aka Good" King Seisyllwg King Deheubarth
Kings Powys: Great x 20 Grand Son of Maredudd ap Bleddyn King Powys 1047-1132
Kings England: Great x 10 Grand Son of King Henry VII of England and Ireland
Kings Scotland: Great x 18 Grand Son of Robert "The Bruce" I King Scotland
Kings Franks: Great x 19 Grand Son of Louis VII King Franks
Kings France: Great x 13 Grand Son of Charles "Beloved Mad" VI King France
Great x 3 Grandfather: William Bentinck 1st Earl of Portland
Great x 2 Grandfather: Henry Bentinck 1st Duke Portland 1682-1726 11 x Great Grand Son of King Edward III of England
Great x 4 Grandfather: Edward Villiers
9 x Great Grand Son of King Edward III of England
Great x 3 Grandmother: Anne Villiers Countess Portland 1651-1688 10 x Great Grand Daughter of King Edward III of England
Great x 4 Grandmother: Frances Howard
9 x Great Grand Daughter of King Edward III of England
Great x 1 Grandfather: William Bentinck 2nd Duke Portland 1709-1762 11 x Great Grand Son of Henry IV King England
Great x 4 Grandfather: Edward Noel 1st Earl Gainsborough
Great x 3 Grandfather: Wriothesley Baptist Noel 2nd Earl Gainsborough 1661-1690 9 x Great Grand Son of Henry IV King England
Great x 4 Grandmother: Elizabeth Wriothesley Countess Gainsborough
8 x Great Grand Daughter of Henry IV King England
Great x 2 Grandmother: Elizabeth Noel Duchess Portland 1688-1737 10 x Great Grand Daughter of Henry IV King England
Great x 4 Grandfather: Fulke Greville 5th Baron Brooke
9 x Great Grand Son of King Edward III of England
Great x 3 Grandmother: Catherine Greville Duchess Buckingham and Normandby 10 x Great Grand Daughter of King Edward III of England
Great x 4 Grandmother: Sarah Dashwood Baroness Brooke
GrandFather: William Cavendish-Bentinck 3rd Duke Portland 9 x Great Grand Son of King Edward IV of England
Great x 4 Grandfather: Edward Harley 9 x Great Grand Son of King Edward III of England
Great x 3 Grandfather: Robert Harley 1st Earl of Oxford and Earl Mortimer 10 x Great Grand Son of King Edward III of England
Great x 2 Grandfather: Edward Harley 2nd Earl of Oxford and Earl Mortimer 11 x Great Grand Son of King Edward III of England
Great x 4 Grandfather: Thomas Foley
Great x 3 Grandmother: Elizabeth Foley Countess of Oxford and Mortimer
Great x 1 Grandmother: Margaret Cavendish Harley 2nd Duchess Portland 1715-1785 8 x Great Grand Daughter of King Edward IV of England
Great x 4 Grandfather: Gilbert Holles 3rd Earl de Clare 1633-1689 8 x Great Grand Son of King Edward III of England
Great x 3 Grandfather: John Holles 1st Duke Newcastle upon Tyne 9 x Great Grand Son of King Edward III of England
Great x 4 Grandmother: Grace Pierrepont Countess de Clare 1633-1702
9 x Great Grand Daughter of King Edward III of England
Great x 2 Grandmother: Henrietta Cavendish Holles Countess of Oxford and Mortimer 1694-1755 7 x Great Grand Daughter of King Edward IV of England
Great x 4 Grandfather: Henry Cavendish 2nd Duke Newcastle upon Tyne 5 x Great Grand Son of King Edward IV of England
Great x 3 Grandmother: Margaret Cavendish Duchess Newcastle upon Tyne 1661-1716 6 x Great Grand Daughter of King Edward IV of England
Great x 4 Grandmother: Frances Pierrepont Duchess Newcastle upon Tyne 1630-1695 9 x Great Grand Daughter of King Edward III of England
Father: William Henry Cavendish-Scott-Bentinck 4th Duke Portland 1768-1854 9 x Great Grand Son of King Henry VII of England and Ireland
Great x 4 Grandfather: William Cavendish 1st Duke Devonshire 9 x Great Grand Son of King Edward III of England
Great x 3 Grandfather: William Cavendish 2nd Duke Devonshire 10 x Great Grand Son of King Edward III of England
Great x 4 Grandmother: Mary Butler Duchess Devonshire
10 x Great Grand Daughter of King Edward III of England
Great x 2 Grandfather: William Cavendish 3rd Duke Devonshire 10 x Great Grand Son of Henry IV King England
Great x 4 Grandfather: William Russell
10 x Great Grand Son of King Edward III of England
Great x 3 Grandmother: Rachel Russell Duchess Devonshire 1674-1725 9 x Great Grand Daughter of Henry IV King England
Great x 4 Grandmother: Rachel Wriothesley 8 x Great Grand Daughter of Henry IV King England
Great x 1 Grandfather: William Cavendish 4th Duke Devonshire 11 x Great Grand Son of Henry IV King England
GrandMother: Dorothy Cavendish 3rd Duchess Portland 1750-1794 8 x Great Grand Daughter of King Henry VII of England and Ireland
Great x 4 Grandfather: Charles Boyle 3rd Baron Clifford
9 x Great Grand Son of King Edward III of England
Great x 3 Grandfather: Charles Boyle 2nd Earl Burlington 5 x Great Grand Son of King Henry VII of England and Ireland
Great x 4 Grandmother: Jane Seymour Baroness Clifford
4 x Great Grand Daughter of King Henry VII of England and Ireland
Great x 2 Grandfather: Richard Boyle 3rd Earl Burlington 6 x Great Grand Son of King Henry VII of England and Ireland
Great x 4 Grandfather: Henry Noel
Great x 3 Grandmother: Juliana Noel Countess Burlington 1672-1750
Great x 1 Grandmother: Charlotte Elizabeth Boyle Marchioness Hartington 7 x Great Grand Daughter of King Henry VII of England and Ireland
Great x 4 Grandfather: George Savile 1st Marquess Halifax
9 x Great Grand Son of King Edward III of England
Great x 3 Grandfather: William Savile 2nd Marquess Halifax 1665-1700 10 x Great Grand Son of King Edward III of England
Great x 4 Grandmother: Dorothy Spencer Lady Savile
9 x Great Grand Daughter of King Edward III of England
Great x 2 Grandmother: Dorothy Savile Countess Burlington 11 x Great Grand Daughter of King Edward III of England
Great x 4 Grandfather: Daniel Finch 2nd Earl Nottingham 7th Earl Winchilsea
10 x Great Grand Son of King Edward III of England
Great x 3 Grandmother: Mary Finch Duchess Roxburghe 1677- 10 x Great Grand Daughter of King Edward III of England
Great x 4 Grandmother: Essex Rich 2nd Countess Nottingham
9 x Great Grand Daughter of King Edward III of England
William John Cavendish-Scott-Bentinck 5th Duke Portland 1800-1879 10 x Great Grand Son of King Henry VII of England and Ireland