Please answer the following question: The answer to the question: What is the last name of the person that created the arbour that is above a Ming dynasty vase? is inside the article: "A symphony in subtle shades of white and green", the White Garden is considered the "most renowned" and most influential of all of Sissinghurst's garden rooms. Planned before the war, it was completed in the winter of 19491950. Using a palette of white, silver, grey, and green, it has been called "one of Vita and Harold's most beautiful and romantic visions". Sackville-West recorded her original inspiration in a letter to Nicolson dated 12 December 1939: "I have got what I hope will be a lovely scheme for it: all white flowers, with some clumps of very pale pink". The concept of single-colour gardens had enjoyed some popularity at the end of the 19th century, but few such gardens remained when Sissinghurst was designed. Influences for the White Garden include Hidcote and Phyllis Reiss's garden at Tintinhull, both of which Vita had seen. Gertrude Jekyll had discussed the concept, but argued for varying the white palette with the use of blue or yellow plants, advice followed by Reiss. But neither Hidcote nor Tintinhull equals the "full-scale symphony" of the White Garden at Sissinghurst. A more prosaic motivation for the colour scheme was to provide reflected illumination for Sackville-West and Nicolson as they made their way from their bedrooms at the South Cottage to the Priest's House for dinner. The focal point of the garden was originally four almond trees, encased in a canopy of the white rose, Rosa mulliganii. By the 1960s, the weight of the roses had severely weakened the trees, and they were replaced with an iron arbour designed by Nigel Nicolson. Beneath the arbour is sited a Ming dynasty vase bought in Cairo. A lead statue of a Vestal Virgin, cast by Toma Rosandic from the wooden original which is in the Big Room, presides over the garden. Sackville-West intended that the statue should be enveloped by a weeping pear tree, Pyrus salicifolia 'Pendula', and the present tree was planted after her original was destroyed in the Great Storm of 1987. Lord considers the White Garden "the most ambitious and..., can you guess it ?
A:
Nicolson