What is the author's style in HITCHCOCK by Helen G. Scott?

The perspective of "Hitchcock" by Francois Truffaut is that of two colleagues having an in-depth but rather informal talk. The way in which the author and subject converse is especially interesting considering that Truffaut is French and did not feel his English was sufficient to conduct the 50-hour long interview with his British subject. In order to communicate properly, Truffaut found a translator who not only spoke both English and French but who could also understand the nuances of the conversation and relay them appropriately.