Robert Armstrong-Jones the Welsh physician was what relation to Antony Armstrong-Jones, 1st Earl of Snowdon?
the grandfather
Title: Antony Armstrong-Jones, 1st Earl of Snowdon
Passage: Antony Charles Robert Armstrong-Jones, 1st Earl of Snowdon, (7 March 1930 – 13 January 2017), commonly known as Lord Snowdon, was a British photographer and film maker.  He was married to Princess Margaret, younger daughter of King George VI and the sister of Queen Elizabeth II.
Title: Robert Armstrong-Jones
Passage: Sir Robert Armstrong-Jones, CBE (born Robert Jones; 2 December 1857 – 31 January 1943) was a Welsh physician and psychiatrist.  He was the grandfather of Antony Armstrong-Jones, 1st Earl of Snowdon (d. 2017).
Title: Earl of Snowdon
Passage: Earl of Snowdon is a title in the Peerage of the United Kingdom.  It was created in 1961, together with the subsidiary title Viscount Linley, of Nymans in the County of Sussex, by Queen Elizabeth II for her then brother-in-law, Antony Armstrong-Jones, who married Princess Margaret in 1960.
Robert Armstrong-Jones Antony Armstrong-Jones, 1st Earl of Snowdon