Robert Armstrong-Jones
Sir Robert Armstrong-Jones, (born Robert Jones; 2 December 1857 – 30 January 1943) was a Welsh physician and psychiatrist.
He was the grandfather of Antony Armstrong-Jones, 1st Earl of Snowdon.
He was born in Ynyscynhaearn, Caernarvonshire, the son of a Congregational minister.
He was educated at Porthmadog Grammar School and Grove Park School, Wrexham, going on to study medicine at University of Wales, Bangor, and St. Bartholomew's Hospital.
Becoming a specialist in the treatment of mental illness, he worked as a junior medical officer at the Royal Earlswood Institution and Colney Hatch during the 1880s, and became resident physician and superintendent of Earlswood Asylum in 1888.
In 1893 he became the first superintendent of the London County Council's Claybury Asylum, where he developed new treatments.
In the same year he married Margaret Roberts (1868–1943), the elder daughter of Sir Owen Roberts of Plas Dinas, Caernarfon.
Armstrong-Jones lectured at St Bartholomew's Hospital, and became consulting physician in mental diseases to the military forces at London and Aldershot.
In 1913, he assumed the additional surname of Armstrong, which had been the maiden name of his wife's mother, Jane Armstrong Roberts, because he wanted to distinguish himself from another prominent Robert Jones of the time.
During World War I, he was designated a Lieutenant-Colonel in the Royal Army Medical Corps; he was knighted in the 1917 New Year Honours, and after the war he was appointed a Commander of the Order of the British Empire (CBE) in recognition of his war service.
He was appointed High Sheriff of Caernarvonshire for 1929.
He was a Fellow of both the Royal College of Physicians and the Royal College of Surgeons.
Armstrong-Jones had one son, Ronald Armstrong-Jones, and two daughters, Elaine Margaret Wauchope (1895–1965) and Gwendolen Jane Buckley (1905–1985), who married Sir Denys Buckley.
Armstrong-Jones died in Plas Dinas at the age of 85.
His wife survived him by only four months.
Their daughter Elaine married Colonel Charles Wauchup.
Armstrong-Jones's son, Ronald, became a barrister, married Anne Messel (firstly) and was the father of Antony Armstrong-Jones, 1st Earl of Snowdon, the brother-in-law of Queen Elizabeth II.
Charles Armstrong-Jones, Viscount Linley
Charles Patrick Inigo Armstrong- Jones, Viscount Linley( born 1 July 1999) is the son of David Armstrong- Jones, 2nd Earl of Snowdon, and Serena Armstrong- Jones, Countess of Snowdon.
He is a great- grandson of King George VI through the king's younger daughter, Princess Margaret, Countess of Snowdon.
He is heir apparent to the Earldom of Snowdon and 22nd in the line of succession to the British throne, after his father.
Ronald Armstrong-Jones
Major Ronald Owen Lloyd Armstrong- Jones,(" né" Jones; 18 May 1899 – 27 January 1966) was a Welsh barrister and soldier.
He was the father of Antony Armstrong- Jones, 1st Earl of Snowdon, and father- in- law of Princess Margaret, younger daughter of George VI.
David Armstrong-Jones, 2nd Earl of Snowdon
David Albert Charles Armstrong-Jones, 2nd Earl of Snowdon (born 3 November 1961), styled as Viscount Linley until 2017 and known professionally as David Linley, is an English furniture maker and a former chairman of the auction house Christie's UK.
The son of Princess Margaret and Antony Armstrong-Jones, 1st Earl of Snowdon, he is therefore a nephew of Queen Elizabeth II, and a grandson of King George VI and Queen Elizabeth
The Queen Mother.
, he is 21st in the line of succession to the British throne, where he is the first person who is not a direct descendant of the Queen.
At the time of his birth in 1961, he was fifth.
Anne Parsons, Countess of Rosse
Anne Parsons, Countess of Rosse(" née" Messel, previously Armstrong- Jones; 8 February 1902 – 3 July 1992), was a society hostess and one of the founders of The Victorian Society and the mother of Antony Armstrong- Jones, 1st Earl of Snowdon.
Princess Margaret, Countess of Snowdon
Princess Margaret, Countess of Snowdon, (Margaret Rose Windsor; 21 August 1930 – 9 February 2002) was the younger daughter of King George VI and Queen Elizabeth and the only sibling of Queen Elizabeth II.
Margaret spent much of her childhood with her parents and sister.
Her life changed dramatically in 1936, when her paternal uncle King Edward VIII abdicated to marry divorcée Wallis Simpson.
Margaret's father became king, and her sister became heir presumptive, with Margaret second in line to the throne.
During the Second World War, the two sisters stayed at Windsor Castle despite suggestions to evacuate them to Canada.
During the war years, Margaret was considered too young to perform any official duties and instead continued her education.
After the war, Margaret fell in love with Group Captain Peter Townsend.
In 1952, her father died, her sister became queen, and Townsend divorced his wife, Rosemary.
He proposed to Margaret early the following year.
Many in the government believed that he would be an unsuitable husband for the Queen's 22-year-old sister, and the Church of England refused to countenance marriage to a divorced man.
Margaret eventually abandoned her plans with Townsend and married photographer Antony Armstrong-Jones in 1960; the Queen made him Earl of Snowdon.
The couple had a son David and a daughter Sarah.
Margaret was often viewed as a controversial member of the British royal family.
Her divorce in 1978 received much negative publicity, and she was romantically associated with several men.
Her health gradually deteriorated in the final two decades of her life.
She was a heavy smoker for most of her adult life and had a lung operation in 1985, a bout of pneumonia in 1993, and at least three strokes between 1998 and 2001.
She died at King Edward VII's Hospital in London after suffering a final stroke on 9 February 2002.
Lady Margarita Armstrong-Jones
Lady Margarita Elizabeth Rose Alleyne Armstrong- Jones( born 14 May 2002) is the only daughter and youngest child of the Earl and Countess of Snowdon.
She is the granddaughter of Princess Margaret and the 1st Earl of Snowdon.
She is currently 23rd in the line of succession to the British throne, after her father and brother.
Serena Armstrong-Jones, Countess of Snowdon
Serena Alleyne Armstrong- Jones, Countess of Snowdon(" née" Stanhope; born 1 March 1970) is an Anglo- Irish aristocrat and the daughter- in- law of Princess Margaret, Countess of Snowdon, and a niece- by- marriage of Queen Elizabeth II and Prince Philip, Duke of Edinburgh.
Thomas Eustace Vesey, 7th Viscount de Vesci
Thomas Eustace Vesey, 7th Viscount de Vesci of Abbeyleix was born on 8 October 1955.
He was the son of John Eustace Vesey, 6th Viscount de Vesci and the former Susan Anne Armstrong- Jones, sister of Antony Armstrong- Jones, 1st Earl of Snowdon.
He sold Abbeyleix Castle, saddled with £ 1.5 million in death duties, in 1994 to the financier Sir David Davies.
He is nephew to Antony Armstrong- Jones, 1st Earl of Snowdon and grand- nephew of Valentine Browne, 6th Earl of Kenmare.'
Despite the sale of Abbeyleix House and Estate, Lord de Vesci continues to promote the heritage of the town.
In 2012, he gave an interview about his family's connection to the town of Abbeyleix to Glenda Gilson for Irishheritagetowns.com.
Lady Sarah Chatto
Lady Sarah Frances Elizabeth Chatto( née Armstrong- Jones; born 1 May 1964) is a member of the extended British royal family.
She is the only daughter of Princess Margaret, Countess of Snowdon, and Antony Armstrong- Jones, 1st Earl of Snowdon, and a niece of Queen Elizabeth II.
At the time of her birth she was seventh in line of succession to the British throne and is currently 24th.

Question: What is the cause of death of David Armstrong-Jones, 2Nd Earl Of Snowdon's mother?
Answer: stroke