question: Who is Christopher Cornford's maternal grandfather?
context: [["Frances Cornford", ["Frances Crofts Cornford (n\u00e9e Darwin; 30 March 1886 \u2013 19 August 1960) was an English poet; because of the similarity of her first name, her father's and her husband's, she was known to her family before her marriage as \"FCD\" and after her marriage as \"FCC\" and her husband Francis Cornford was known as \"FMC\".", "Her father Sir Francis Darwin, a son of Charles Darwin, yet another 'Francis', was known to their family as \"Frank\", or as \"Uncle Frank\"."]], ["Kaya Alp", ["Kaya Alp was, according to Ottoman tradition, the son of K\u0131z\u0131l Bu\u011fa and the father of Suleyman Shah, who was, in turn, the grandfather of Ertu\u011frul, and the great grandfather of the Ottoman Empire founder, Osman I."]], ["Henry Bryant (naturalist)", ["Henry Bryant( May 12, 1820 \u2013 February 2, 1867) was an American physician and naturalist.", "He was the grandfather of Henry Bryant Bigelow."]], ["Lyon Cohen", ["Lyon Cohen( 1868\u20131937) was a Polish- born Canadian businessman and a philanthropist.", "He was the grandfather of singer/ poet Leonard Cohen."]], ["Prithvipati Shah", ["Prithvipati Shah( ?\u20131716) was the king of the Gorkha Kingdom in the Indian subcontinent, present- day Nepal.", "He was the grandfather of Nara Bhupal Shah."]], ["Fujiwara no Nagara", [", also known as Fujiwara no Nagayoshi, was a Japanese statesman, courtier and politician of the early Heian period.", "He was the grandfather of Emperor Y\u014dzei."]], ["Abd al-Muttalib", ["Abd al- Muttalib Shaybah ibn Hashim( c. 497 \u2013 578) was the grandfather of Islamic prophet Muhammad."]], ["Christopher Cornford", ["Christopher Francis Cornford (9 February 1917 \u2013 8 April 1993) was a British artist and writer.", "He was the son of Francis Cornford, and his wife Frances Cornford (n\u00e9e Darwin).", "Through his mother he was a great-grandson of the naturalist Charles Darwin.", "His elder brother was the poet, communist, and Spanish Civil War", "victim John Cornford.", "His son is Adam Cornford, British poet, librettist, and essayist.", "He was active in politics until into the late 1980s, in the Campaign for Nuclear Disarmament and its offshoot Cambridge Against Missile Bases, and in the environmental movement as a signatory of the Blueprint for Survival and an early member of the Ecology (later Green) Party in the UK.", "Christopher Francis Cornford was cremated on 19 April 1993 at Cambridge Crematorium."]], ["Guillaume Wittouck", ["Guillaume Wittouck( 1749- 1829) was a Belgian lawyer and High Magistrate.", "He was the Grandfather of industrialist Paul Wittouck."]], ["John Westley", ["Rev. John Westley( 1636 \u2013 78) was an English nonconformist minister.", "He was the grandfather of John Wesley( founder of Methodism)."]]]
supporting_facts: [["Christopher Cornford", 1], ["Frances Cornford", 1]]
evidences: [["Christopher Francis Cornford", "mother", "Frances Cornford"], ["Frances Cornford", "father", "Francis Darwin"]]
answer: Francis Darwin