Given the question: What is the last name of the person Diana cheats on with Miles?  Answer the above question based on the context below:  Diana Scott is a beautiful, bored young model married to Tony Bridges. One day, Diana meets Robert Gold, a literary interviewer/director for television arts programmes, by chance when she is spotted on the street by his roving film crew and interviewed by him about young people's views on convention. Diana is invited to watch the final edit in the TV studio and there their relationship starts. After liaisons in bleak hotel rooms they leave their spouses (and, in Robert's case, children) and move into an apartment. As a couple, they become part of the fashionable London media/arts set. Initially, Diana is jealous when Robert sees his wife while visiting his children, but she quickly loses this attachment when she mixes with the predatory males of the media, arts and advertising scene, particularly Miles Brand, a powerful advertising executive for the "Glass Corporation" who gets her a part in a trashy thriller after she has sex with him. The bookish Robert prefers the quiet life; it is he who now becomes jealous, but increasingly detached, depressed and lonely. Diana attends a high-class charity draw for world hunger for which she is the face. The event, adorned by giant images of African famine victims, is at the height of cynical hypocrisy and bad taste, showing Diana's rich white set, which now includes the establishment, playing at concern, gorging themselves, gambling and generally behaving decadently. Already showing signs of stress from constantly maintaining the carefree look demanded by the false, empty lifestyle to which she has become a prisoner, Diana becomes pregnant, and has an abortion.
The answer is:
Gold