Georgiana Maxwell, 26th Baroness de Ros
Georgiana Angela Maxwell, 26th Baroness de Ros of Helmsley(" née Ross")( 2 May 1933 – 21 April 1983), succeeded her grandmother Una Ross after the title was called out of abeyance in her favour in 1958.
She was the first woman of her line to be allowed to sit in the House of Lords after the Peerage Act 1963.
She studied at Wycombe Abbey and Studley Royal Agricultural College.
She gained a National Diploma in Dairying.
The 26th Baroness was the daughter of Lieutenant- Commander The Hon. Peter Ross, RN, who himself was the eldest son of the 25th Baroness.
Georgiana married Commander John David Maxwell of the Royal Navy on 24 July 1954 and they had two children:
Tjuyu
Tjuyu( sometimes transliterated as Thuya or Thuyu) was an Egyptian noblewoman and the mother of queen Tiye, and the wife of Yuya.
She is the grandmother of Akhenaten, and great grandmother of Tutankhamun.
Everard de Ros
Everard de Ros( born 1145) was the lord of Hamlake.
Peter Maxwell, 27th Baron de Ros
Peter Trevor Maxwell, 27th Baron de Ros (born 23 December 1958) is the premier baron of England, by virtue of Baron de Ros being the oldest baronial title created in the Peerage of England.
He is the son of Lieutenant-Commander John David Maxwell, RN and of Lady de Ros, a "suo jure" peeress.
The 27th Baron was educated at Headfort School, in Kells, Ireland, as well as Down High School, in Downpatrick, Northern Ireland before going to a boarding school in the Republic of Ireland.
On 5 September 1987, the Lord de Ros married Angela Sián Ross, and they have three children:
Dudley FitzGerald-de Ros, 23rd Baron de Ros
Dudley Charles FitzGerald-de Ros, 23rd Baron de Ros of Helmsley, (11 March 1827 – 29 April 1907) was a soldier, courtier and the premier Baron of England.
Henry FitzGerald-de Ros, 21st Baron de Ros
Henry William FitzGerald -de Ros, 21st
Baron de Ros( 12 June 1793 – 28/29 March 1839) was a British nobleman, the son of Lord Henry FitzGerald and his wife Charlotte FitzGerald- de Ros, 20th Baroness de Ros. Fitzgerald- de Ros briefly served as Member of Parliament for the borough of West Looe from 1816 to 1818.
In 1831, upon the death of his mother, he inherited the Barony of de Ros, the oldest surviving barony in the Peerage of England.
He was an excellent whist player, but was involved in a gambling scandal in 1836.
Lord de Ros was accused of cheating at Graham's Club by the trick of" sauter la coupe", and by marking the cards with his thumbnail.
He sued his accusers for libel, but lost the case.
He died not long after, and was commemorated by Theodore Hook with the punning epitaph," Here lies the premier baron of England, patiently awaiting the last trump."
He died in London, unmarried and without issue.
Hannah Arnold
Hannah Arnold, also known as Hannah Waterman King, was the grandmother of Benedict Arnolds children.
Mary Dawson, Countess of Dartrey
Mary Frances Dawson, Countess of Dartrey, 24th Baroness de Ros of Helmsley ("née FitzGerald-de Ros")
(31 July 1854 – 4 May 1939) was a British peer.
She was born in London.
Her parents were Dudley FitzGerald-de Ros and Lady Elizabeth Egerton.
Upon her father's death in 1907, Mary succeeded to the title.
The 24th Baroness married Anthony Dawson, 3rd Earl of Dartrey (1855–1933) in London on 2 October 1878.
To them were born three daughters; the Barony of de Ros descended among their issue:
Hubba bint Hulail
Hubba bint Hulail was the grandmother of Hashim ibn' Abd Manaf, thus the great- great- great- grandmother of the Islamic" Nabī"( Prophet) Muhammad ibn Abdullah.
Una Ross, 25th Baroness de Ros
Una Mary Ross, 25th Baroness de Ros of Helmsley (born "Lady Una Mary Dawson")
(5 October 1879 – 9 October 1956) succeeded her mother to the title in 1943.
She was the daughter of Anthony Lucius Dawson, 3rd Earl of Dartrey and Mary Dawson, who held the barony in her own right.
The 25th Baroness married Arthur John Ross (killed in action 1917) on 30 July 1904, and they had at least two children:

Question: Who is Una Ross, 25Th Baroness De Ros's maternal grandmother?
Answer: Lady Elizabeth Egerton