I came across this in a grammar exercise, and I am fairly certain that the past simple would be better, but I want your opinion. The answer key gives me the past perfect, but I don't see the need for it.
- He went to see them in their offices, and as soon as he sat down, the two directors took out a map of the Singapore circuit.
- He went to see them in their offices, and as soon as he had sat down, the two directors took out a map of the Singapore circuit.
To me, the past perfect is not necessary because the events are in order here and we aren't talking about an event that is out of order that happened before the main events. The past perfect seems a little clunky to me, especially because of the phrase "as soon as he..." which implies that the two past events occurred at about the same moment.