I was in Brazil when this thread started, but to answer your original question, Dawn Whitelaw, an outstanding artist, uses a limited palette in her plein air and portrait work. Her colors are:
Utrecht Cadmium Yellow light
Winton #6
Cadmium Red Deep Hue (Napthal Red)
Ultramarine Blue
Titanium White.
You can see examples of her landscape limited palette paintings at:
http://www.brazierfineart.com/whitelaw.shtml
Her Best of Show prize winning portrait (also limited palette) from the Portrait Society of America Conference, 2001:
http://www.portraitsociety.org/2001winners/whitelaw.htm
Stunning work.
Peggy