Question: Who is Archibald Acheson, 4Th Earl Of Gosford's paternal grandfather?

Knowledge 1: Archibald Acheson, 4th Earl of Gosford
Archibald Brabazon Sparrow Acheson, 4th Earl of Gosford, (2 August 1841 – 11 April 1922) was a British peer.The son of Archibald Acheson, 3rd Earl of Gosford, he was born at Worlingham Hall, Suffolk, in 1841, and succeeded to the earldom upon the death of his father in 1864.Since there are two United Kingdom peerages (e.g. Baron Worlingham) subsumed in that Irish Earldom, he was entitled to an automatic seat in the House of Lords.He was Lord Lieutenant of Armagh from 1883 to 1920, and served as Vice-Chamberlain of the Household of Queen Alexandra from 1901.He was Honorary Colonel of the 3rd Battalion of the Royal Irish Fusiliers from 1899, and Vice-Admiral of Ulster.Gosford died in London in 1922, aged 80, and was cremated at Golders Green Crematorium. [SEP] Knowledge 2: Archibald Acheson, 3rd Earl of Gosford
Archibald Acheson, 3rd Earl of Gosford KP (20 August 1806 – 15 June 1864), styled Viscount Acheson between 1807 and 1849, was a British peer and Member of Parliament.He was the only son of Archibald Acheson, 2nd Earl of Gosford of Gosford Castle, County Armagh and educated at Harrow School and Christ Church, Oxford.He succeeded to his father's Irish titles and estates in 1849.He was elected in 1830 as the Member of Parliament for County Armagh in the British House of Commons, a seat he held until 1847, when he was ennobled as 1st Baron Acheson, of Clancairney, County Armagh, in the Peerage of the United Kingdom.He was created a Knight of the Order of St. Patrick in 1855.He was appointed lord-lieutenant and custos rotulorum of co. Armagh from February 1864 to his death later that year.He married Theodosia, daughter of John Brabazon, 10th Earl of Meath, on 22 June 1832, with whom he had seven children:
Knowledge 1: Archibald Acheson, 4th Earl of Gosford
Archibald Brabazon Sparrow Acheson, 4th Earl of Gosford, (2 August 1841 – 11 April 1922) was a British peer.The son of Archibald Acheson, 3rd Earl of Gosford, he was born at Worlingham Hall, Suffolk, in 1841, and succeeded to the earldom upon the death of his father in 1864.Since there are two United Kingdom peerages (e.g. Baron Worlingham) subsumed in that Irish Earldom, he was entitled to an automatic seat in the House of Lords.He was Lord Lieutenant of Armagh from 1883 to 1920, and served as Vice-Chamberlain of the Household of Queen Alexandra from 1901.He was Honorary Colonel of the 3rd Battalion of the Royal Irish Fusiliers from 1899, and Vice-Admiral of Ulster.Gosford died in London in 1922, aged 80, and was cremated at Golders Green Crematorium. [SEP] Knowledge 2: Thomas Stewart, Master of Mar
Thomas married Elizabeth, the widow of John Stewart, 2nd Earl of Buchan, who was daughter of Archibald Douglas, 4th Earl of Douglas and Margaret Stewart, Lady of Galloway.They were required to obtain a marriage license, which was granted on 1 May 1427, due to their degrees of consanguinity and affinity.He had a son.
Knowledge 1: Archibald Acheson, 3rd Earl of Gosford
Archibald Acheson, 3rd Earl of Gosford KP (20 August 1806 – 15 June 1864), styled Viscount Acheson between 1807 and 1849, was a British peer and Member of Parliament.He was the only son of Archibald Acheson, 2nd Earl of Gosford of Gosford Castle, County Armagh and educated at Harrow School and Christ Church, Oxford.He succeeded to his father's Irish titles and estates in 1849.He was elected in 1830 as the Member of Parliament for County Armagh in the British House of Commons, a seat he held until 1847, when he was ennobled as 1st Baron Acheson, of Clancairney, County Armagh, in the Peerage of the United Kingdom.He was created a Knight of the Order of St. Patrick in 1855.He was appointed lord-lieutenant and custos rotulorum of co. Armagh from February 1864 to his death later that year.He married Theodosia, daughter of John Brabazon, 10th Earl of Meath, on 22 June 1832, with whom he had seven children: [SEP] Knowledge 2: Archibald Primrose, 4th Earl of Rosebery
Archibald John Primrose, 4th Earl of Rosebery, KT, PC, FRS( 14 October 1783 – 4 March 1868), styled Viscount Primrose until 1814, was a British politician.He was the eldest son of Neil Primrose, 3rd Earl of Rosebery, and his second wife, Mary Vincent.Primrose was educated at Pembroke College, Cambridge, gaining his MA in 1804.He was Member of Parliament for Helston from 1805 to 1806 and Cashel from 1806 to 1807.He succeeded to the earldom in 1814, and was created Baron Rosebery, of Rosebery in the County of Edinburgh, in the Peerage of the United Kingdom, in 1828.He was appointed a Privy Counsellor in 1831 and a Knight of the Thistle in 1840.He was a Fellow of the Royal Society.He was the grandfather of Archibald Primrose, 5th Earl of Rosebery, who served as Prime Minister of the United Kingdom from 1894 to 1895.

Answer: Archibald Acheson, 2nd Earl of Gosford