I have to laugh at the comments about Diana's fashion in the 80's. I was just out of university when Diana and Charles married, seriously interested in fashion, and I was appalled by her clothes: ruffles, bows, cutesy Laura Ashley prints and novelty sweaters, white tights. She dressed in clothes that were either far too young for her (that included the wedding dress) or far too old -- stiff suits and hats. It took a decade for her to hit her stride, and by then, she was nearly divorced.
I wasn't a Diana fan from the get-go, but to be fair, we were all coming out of a decade -- the 70's -- in which everyone had looked terrible (despite the efforts, in the US, of a few designers like Calvin Klein, Ralph Lauren, and Diane von Furstenburg), and in the 80's, most people were floundering around, grasping at a renewed sense of style but uncertain how to achieve it. We were assailed, on the one hand, by notions of "professional dress" for the many newly professional women (remember all those stiff little skirt suits with bow ties?), and on the other by a concerted but not very well managed "return to glamour".
I think we can be grateful that style now is no longer a matter of following any particular trends, but rather of wearing what looks good, chosen from the wide variety of choices available. I recall that someone -- in the New York Times, I think -- commented perhaps a dozen years ago that good style in clothes, interior design, and so forth, is now available to everyone, at reasonable prices, whereas only 2 or 3 decades ago, you still needed a lot of money to achieve it, and even then you might not get it right, as Diana did not. I liked the fact that the Duchess of Cambridge, during the years before her engagement, usually looked good and stylish, often in clothes that didn't cost a great deal, and I liked the fact that I, too, could buy elegant, well-made clothes that didn't break my personal bank. Younger women may not realize how hard that was to do a few decades ago. You had to be very serious about scouting the possibilities; it helped if you had immediate access to shops in major cities (no online buying); and even then, you had to pay more than women in their 20's may have available to spend.
We are all far better off now than we were, and so are the royals. The reason that the Duchess of Cambridge can wear relatively inexpensive clothes and look great in them is that real style has trickled down to the mass market -- to her and to us. Genuinely stylish mass market clothes were very hard to find 30 years ago, and after the late 60's and the 70's, few people really had a sense of what "genuinely stylish" might mean. Now, we all can achieve it, if we have some taste.