I always do 2-3 coats of paint, I went from cream (inherited with house) to a grey duck egg blue, first coat looked awful, second coat didn't look any better, very patchy. Third coat looks amazing.
I have always used crown/dulux paints and never had a problem with it being patchy after a 3rd coat. You will need the 3 coats as you are going from very light to very dark.
Although I am no property developer I have painted a hell of a lot of rooms 