Trinny and Susannah are not the authorities they'd like to think they are (remember they infamously advised wearing pigtails, a dress over jeans, and a bag with a cat on it to a job interview?) But I recall they once said that dressing like a teenager when you're an adult just makes it look like you don't know who you are, that's very trueAdults who adopt teenage trends.
Conversely, I hate the idea that women over 30 or 40 need to "cover up" and dress a certain way. Not too long ago I read an article about "appropriate" dressing after age 30 which advocated wearing hideous clothes (prairie dresses, ankle-length skirts) "unless you have a figure like Kim Kardashian." Piss off!