Annie Maud Cargill Harris1,2 
From 1900, her married name became Duff.1
- [S1438] Sir William, Bt. Arbuthnot, “re: Arbuthnot and Duff Families,” e-mail message to British and European Nobility Register, 29 August 2005 and later. Hereinafter cited as “re: Arbuthnot and Duff Families.”
- [S7535] Judy Wright, “re: Harris Family,” e-mail message to Judy Wright, 17 April 2015. Hereinafter cited as “re: Harris Family.”
Lt.-Cdr. Malcolm John Luxmoore Duff1 
He gained the rank of Lieutenant-Commander in the Royal Navy.1
- [S1438] Sir William, Bt. Arbuthnot, “re: Arbuthnot and Duff Families,” e-mail message to British and European Nobility Register, 29 August 2005 and later. Hereinafter cited as “re: Arbuthnot and Duff Families.”
Angela E. P. Bate1
From 1947, her married name became Duff.1
- [S1438] Sir William, Bt. Arbuthnot, “re: Arbuthnot and Duff Families,” e-mail message to British and European Nobility Register, 29 August 2005 and later. Hereinafter cited as “re: Arbuthnot and Duff Families.”
Elizabeth Harriet Penrose-Thackwell1
Her married name became Duff.1
- [S1438] Sir William, Bt. Arbuthnot, “re: Arbuthnot and Duff Families,” e-mail message to British and European Nobility Register, 29 August 2005 and later. Hereinafter cited as “re: Arbuthnot and Duff Families.”
Thomas Abercromby Duff1 
Child of Thomas Abercromby Duff and Mary Gordon
- Colonel Alexander Gordon Duff+1 b. 28 Aug 1828, d. Aug 1904
- [S1438] Sir William, Bt. Arbuthnot, “re: Arbuthnot and Duff Families,” e-mail message to British and European Nobility Register, 29 August 2005 and later. Hereinafter cited as “re: Arbuthnot and Duff Families.”
Mary Gordon1 
From 1825, her married name became Duff.1
Child of Mary Gordon and Thomas Abercromby Duff
- Colonel Alexander Gordon Duff+1 b. 28 Aug 1828, d. Aug 1904
- [S1438] Sir William, Bt. Arbuthnot, “re: Arbuthnot and Duff Families,” e-mail message to British and European Nobility Register, 29 August 2005 and later. Hereinafter cited as “re: Arbuthnot and Duff Families.”
Colonel Alexander Gordon Duff1 
Children of Colonel Alexander Gordon Duff and Eliza Phillips
- Nora Beatrice Gordon Duff1 b. c 1869
- Robert Harold Ambrose Gordon Duff+1 b. 1871
- Arthur Allan Morison Duff+1 b. 1874
- [S1438] Sir William, Bt. Arbuthnot, “re: Arbuthnot and Duff Families,” e-mail message to British and European Nobility Register, 29 August 2005 and later. Hereinafter cited as “re: Arbuthnot and Duff Families.”
Eliza Phillips1 
From 1866, her married name became Duff.1
Children of Eliza Phillips and Colonel Alexander Gordon Duff
- Nora Beatrice Gordon Duff1 b. c 1869
- Robert Harold Ambrose Gordon Duff+1 b. 1871
- Arthur Allan Morison Duff+1 b. 1874
- [S1438] Sir William, Bt. Arbuthnot, “re: Arbuthnot and Duff Families,” e-mail message to British and European Nobility Register, 29 August 2005 and later. Hereinafter cited as “re: Arbuthnot and Duff Families.”
Mark Phillips1
Child of Mark Phillips and Maria Gumbleton
- Eliza Phillips+1 b. 1837, d. 1910
- [S1438] Sir William, Bt. Arbuthnot, “re: Arbuthnot and Duff Families,” e-mail message to British and European Nobility Register, 29 August 2005 and later. Hereinafter cited as “re: Arbuthnot and Duff Families.”
Maria Gumbleton1
Child of Maria Gumbleton and Mark Phillips
- Eliza Phillips+1 b. 1837, d. 1910
- [S1438] Sir William, Bt. Arbuthnot, “re: Arbuthnot and Duff Families,” e-mail message to British and European Nobility Register, 29 August 2005 and later. Hereinafter cited as “re: Arbuthnot and Duff Families.”