Question: Harold Siddons is a descendant of which Welsh-born actress?

Context paragraphs:
Sarah Siddons: Sarah Siddons (5 July 1755 – 8 June 1831) was a Welsh-born actress, the best-known tragedienne of the 18th century.  She was the elder sister of John Philip Kemble, Charles Kemble, Stephen Kemble, Ann Hatton and Elizabeth Whitlock, and the aunt of Fanny Kemble.  She was most famous for her portrayal of the Shakespearean character, Lady Macbeth, a character she made her own, and for famously fainting at the sight of the Elgin Marbles in London.  The Sarah Siddons Society continues to present the Sarah Siddons Award in Chicago every year to a prominent actress.

Peggy Cummins: Peggy Cummins (born 18 December 1925) is a retired Welsh-born Irish actress, best known for her performance in Joseph H. Lewis's "Gun Crazy" (1949), playing a trigger-happy "femme fatale", who robs banks with her lover (played by John Dall).

Sarah Siddons Award: The Sarah Siddons Society is an American non-profit organization founded in 1952 by prominent Chicago theatre patrons with the goal of promoting excellence in the theatre.  Since 1952, the Society has presented the Sarah Siddons Award annually to an actor for an outstanding performance in a Chicago theatrical production.  The winner receives a statuette of the Welsh stage actress Sarah Siddons.

Harold Siddons: Harold Siddons (17 September 1922 – 4 November 1963) was a British film and television actor, appearing in "Genevieve", "The Dam Busters", "Appointment in London", "They Who Dare", "The Purple Plain", "Quatermass and the Pit", "A Night To Remember" and "The Wrong Arm of the Law".  He was an RAF pilot during the Second World War and a descendant of Sarah Siddons.

Penelope Mortimer: Penelope Ruth Mortimer (née Fletcher, 19 September 1918 – 19 October 1999) was a Welsh-born English journalist, biographer, and novelist.  She wrote a semi-autobiographic novel in 1962 entitled "The Pumpkin Eater", which was turned into a 1964 film, for which Anne Bancroft was nominated for the Academy Award for Best Actress for her performance as "Jo Armitage", a character based on Mortimer herself.

Margaret Phillips: Margaret Phillips (6 July 1923 – 9 September 1984) was a Welsh-born actress who was active on Broadway from the 1940s and in television in the 1950s and 1960s.

Phoebe Davies: Phoebe Davies (February 7, 1864 – December 4, 1912) was a Welsh-born American stage actress who starred in over 4,000 performances of the Lottie Blair Parker play, "Way Down East".

Sarah Edwards (actress): Sarah Edwards (October 11, 1881 – January 7, 1965) was a Welsh-born American film and stage actress.  She often played dowagers or spinsters in numerous Hollywood movies of the 1930s and 1940s, mostly in minor roles.

Harriet Siddons: Harriet Siddons (née Murray; 16 April 1783 2 November 1844), sometimes known as Mrs Henry Siddons, was a Scottish actress and theatre manager.

To Mrs Siddons: "To Mrs Siddons" was written by Samuel Taylor Coleridge and published in the 29 December 1794 "Morning Chronicle" as part of the "Sonnets on Eminent Characters" series.  It describes Sarah Siddons, an actress that Coleridge became fond of during his visits to London during college.  The poem celebrates watching Siddons perform her various roles on stage.  It is uncertain as to the actual authorship of the poem, since it was attributed to Charles Lamb in various works.  It is possible that Lamb and Coleridge worked on the poem together, and it would represent one of Lamb's earliest works.

Supporting paragraphs: Harold Siddons Sarah Siddons
Answer: Sarah Siddons