Task: Question Generation
Input (English): Passage: The Tower is of brick and was the entrance to the cour d'honneur of the 1560s rebuilding. Of four storeys, it has recessed staircase turrets to each side, creating what the architectural historian Mark Girouard described as an "extraordinarily slender and elegant" appearance. The courtyard was open on the tower side, its three facades containing seven classical doorways. Girouard notes Horace Walpole's observation of 1752, "perfect and very beautiful". Such an arrangement of a three-sided courtyard with a prominent gatehouse set some way in front became popular from Elizabethan times, similar examples being Rushton Hall and the original Lanhydrock.The Tower was Sackville-West's sanctum; her study was out of bounds to all but her dogs and a small number of guests by invitation. Her writing room is maintained largely as it was at the time of her death. Nigel Nicolson records his discovery in the Tower of his mother's manuscript describing her affair with Violet Trefusis. This went on to form the basis of his book Portrait of a Marriage. The clock, below the Tower parapet, was installed in 1949. A plaque is affixed to the arch of the Tower; the words were chosen by Harold Nicolson: "Here lived V. Sackville-West who made this garden". Nigel Nicolson always felt that the memorial failed to acknowledge his father's contribution. The Tower has a Grade I listing.
Output (English): What is the last name of the person who had an affair with Violet?