Task: Question Answering
Input (English): Passage: Vita Sackville-West, poet, author, and gardener, was born at Knole, about 25 miles from Sissinghurst, on 9 March 1892. The great Elizabethan mansion, home of her ancestors but denied to her through agnatic primogeniture, held enormous importance for her throughout her life. Sissinghurst was a substitute for Knole, and she greatly valued its familial connections. In 1913 Sackville-West married Harold Nicolson, a diplomat at the start of his career. Their relationship was unconventional, with both pursuing multiple, mainly same-sex, affairs. After breaking with her lover Violet Trefusis in 1921, Sackville-West became increasingly withdrawn. She wrote to her mother that she would like "to live alone in a tower with her books", an ambition she achieved in the tower at Sissinghurst where only her dogs were regularly admitted.
From 1946 until a few years before her death, Sackville-West wrote a gardening column for The Observer, in which, although she never referred directly to Sissinghurst, she discussed a wide array of horticultural issues. In an article, "Some Flowers", she discussed the challenge of writing effectively about flowers: "I discovered this only when I started to do so. Before ... I found myself losing my temper with the nauseating phraseology ... and sickly vocabulary employed." In 1955, in recognition of her achievement at Sissinghurst, "bending some stubborn acres to my will", she was awarded the Royal Horticultural Society's Veitch Medal. Her biographer Victoria Glendinning considers Sissinghurst to be Sackville-West's "one magnificent act of creation". 
Question: What is the last name of the person who wrote to her mother that she would like "to live alone in a tower with her books"?
Output (English): Sackville-West.