Please answer the following question: Given the following context:  The management of Rockefeller Center shifted around this time. In November 1936, John Todd was featured in two New Yorker articles that emphasized his role in the complex's construction. At the same time, Nelson was gaining clout within Rockefeller Center Inc., and he disagreed with nearly all of Todd's suggestions. Nelson's father, John, was relinquishing his responsibilities, since the Rockefeller family's youngest son David had moved out of the family home at 10 West 54th Street, and John was now focusing on his own personal life. By April 1937, Todd regretted his decision to be featured in The New Yorker. In March 1938, Nelson became the president of Rockefeller Center Inc. He then fired Todd as the complex's manager and appointed Hugh Robertson in his place. Nelson and Robertson wanted to avoid workers' strikes, which would delay the completion of construction. Nelson, Robertson, and the workers' unions agreed to a contract in which the unions would not strike, Robertson would not lock out union workers, and both would agree to arbitration if a labor dispute arose. Rockefeller Center was one of Nelson's primary business ventures until 1958, when he was elected Governor of New York.Public relations officials were hired to advertise the different parts of the complex, such as the gardens and the plaza. Merle Crowell set up a viewing platform on the east side of Rockefeller Center and founded the facetious "Sidewalk Superintendents' Club" so the public could view construction.  answer the following question:  What is the first name of the person in whose place Hugh Robertson was appointed complex manager at Rockefeller Center?
Answer:
John