Question: Who is Ian Leslie, 21St Earl Of Rothes's paternal grandfather?

Context paragraphs:
title: John Chetwynd-Talbot, 21st Earl of Shrewsbury
paragraph_text: John George Chetwynd- Talbot, 21st Earl of Shrewsbury, 21st Earl of Waterford, 6th Earl Talbot( 21 January 1914 – 12 November 1980), styled Viscount of Ingestre from 1915 to 1921, was a British peer.
title: John Leslie, 1st Duke of Rothes
paragraph_text: John Leslie( c. 163027 July 1681), son of John Leslie, 6th Earl of Rothes, was the 7th Earl of Rothes and 1st Duke of Rothes. According to tradition, he was a descendant of Princess Beatrix, sister of King Malcolm III of Scotland. His family had intermarried with both the Stuarts and the Bruces.
title: Jane Elizabeth Leslie, 12th Countess of Rothes
paragraph_text: Jane Elizabeth Leslie, 12th Countess of Rothes( 5 May 1750 – 1810) was a Scottish noblewoman. She was the daughter of John Leslie, 10th Earl of Rothes and his first wife Hannah Howard, daughter of Matthew Howard of Thorp, Norfolk, and his wife Britannia Cole. She succeeded her brother, John Leslie, 11th Earl of Rothes, in 1773 in the peerage and estates of Rothes, and effectually vindicated her right to the estates against the claim of her uncle Andrew Leslie, both in the Court of Session and the House of Lords. She was twice married, first in 1766, to George Raymond Evelyn, youngest son of William Evelyn Glanville of St Clere, Kent, and secondly, in 1772, to Sir Lucas Pepys, 1st Baronet, an eminent physician and uncle of the first Earl of Cottenham. By both marriages she had issue, and dying in 1810, was succeeded by the only surviving son of her first marriage, George William, 13th Earl of Rothes.
title: Malcolm Leslie, 20th Earl of Rothes
paragraph_text: Malcolm George Dyer-Edwardes Leslie, 20th Earl of Rothes (1902 – 1975) was a Scottish nobleman, and the head of Clan Leslie. He was the Earl of Rothes from 1927-1975 following the death of his father, Norman Leslie, 19th Earl of Rothes. His mother was Noël Leslie, Countess of Rothes, who not only survived the "Titanic" disaster, but took the till of a lifeboat and helped row survivors to the "RMS Carpathia". His son succeeded him in 1975 as the Earl of Rothes. On 17 July 1926, he married Beryl Dugdale, daughter of Lionel Dugdale of Crathorne, a former High Sheriff of Yorkshire, and sister of Thomas Dugdale, 1st Baron Crathorne. They had three children: He worked as Chairman of the National Mutual Life Assurance Society. He succeeded as the 20th Earl of Rothes on the death of his father in 1927. He served as a Representative Peer for Scotland until this system was abolished. The Earl died on 7 May 1975. The Rothes Chair in Preventive Ophthalmology was established at London University in his memory in 1977.
title: Ralph Neville, 3rd Earl of Westmorland
paragraph_text: Ralph Neville, 3rd Earl of Westmorland( c. 1456 – 6 February 1499) was an English peer. He was the grandfather of Ralph Neville, 4th Earl of Westmorland.
title: William Leslie, 3rd Earl of Rothes
paragraph_text: William Leslie( died 1513), 3rd Earl of Rothes, was the son of Andrew Leslie, Master of Rothes, and Marjory( also known as Elizabeth) Sinclair, daughter of William Sinclair, 1st Earl of Caithness. He succeeded his elder brother George as Earl in 1513. As George had tried to sell the family lands without royal permission William was trying to recover his rights, especially over the Barony centred on Ballinbreich Castle. However, he was killed at the battle of Flodden. William married Margaret Balfour, his heir was George Leslie, 4th Earl of Rothes. Their other children included John Leslie of Parkhill who was captured at the battle of Solway Moss, and James Leslie, Parson of Rothes.
title: George Leslie, 2nd Earl of Rothes
paragraph_text: George Leslie, 2nd Earl of Rothes( died 1513) was a Scottish peer. He was the son of Andrew Leslie, Master of Rothes and Marjorie Sinclair( daughter of William Sinclair, 1st Earl of Caithness), and the grandson of George Leslie, 1st Earl of Rothes. George was invested in his lands as Earl of Rothes on 25 May 1492. In 1498 George was summoned to trial for the murder of George Leslie alias Dunlop, and failed to appear in subsequent years. In 1509, the Leslie lands were" recognized" by James IV of Scotland. The King took back the family's feudal title because George had tried to sell the lands without permission. Chief amongst the lands was the title of the Barony of Ballinbreich Castle. George died unmarried before March 1513, and was succeeded as Earl by his brother, William.
title: George Leslie, 1st Earl of Rothes
paragraph_text: George Leslie, 1st Earl of Rothes( c. 1406/1417 – 1490) was a Scottish nobleman and the first to hold the title of" Earl of Rothes", a hereditary title of the ruler of Leslie, Fife and the lands belonging to the Earl of Rothes.
title: Ian Leslie, 21st Earl of Rothes
paragraph_text: Ian Lionel Malcolm Leslie, 21st Earl of Rothes( 10 May 1932 – 15 April 2005) was a Scottish nobleman. The eldest son of the 20th Earl and Beryl Dugdale, he was educated at Eton and was a Sub- Lieutenant in the Royal Naval Volunteer Reserve from 1953. In 1955 he married Marigold Evans- Bevan of Wales, daughter of Sir David Evans- Bevan. They had two sons: James( b. 1958) and Alexander( b. 1962).
title: George Leslie, 15th Earl of Rothes
paragraph_text: George William Evelyn Leslie, 15th Earl of Rothes (8 November 1809 – 10 March 1841) was the son of Henrietta Leslie, 14th Countess of Rothes and George Gwyther. He was christened on 14 December at Saint Mary-St Marylebone Road, St Marylebone, London, England.
Leslie succeeded his mother Henrietta Anne, to the title Earl of Rothes, in 1819. On 7 May 1831, he married Louisa Susannah Jane Anderson Morshead, daughter of Henry Anderson Morshead, and they had issue:

Reasoning steps:
Ian Lionel Malcolm Leslie, 21st Earl of Rothes father 20th Earl
Malcolm Leslie, 20th Earl of Rothes father Norman Leslie, 19th Earl of Rothes

Answer: spans: Norman Leslie, 19th Earl of Rothes