Red just always looks better with black. Makes the red look more modern and a little edgier.
Please do not insult the memory of Princess Diana by comaring her and Catherine. While Catherine may be pretty and style conscious, Diana in her very short 36 years did so much for the people, her Country and the beautiful impression she left on her sons. Also let's remember she did not have the support from a loving husband....none of us know what went on behind the scenes but we do know what we saw and Diana held her own during the most horrible times.
Kate is much more attractive. She looks like a woman while Diana has some issue with her face. Due to generations past of inbreading to keep the lineage intact.