Mathilde always comes across was vey classical. It is often hard to believe (from her style) that she is not 60+, but she is actually young. Within that style, she looks great when it comes to classical colours and cuts. Obviously it is not interesting, but looks good. If she tries something, like the tartan thing, it tends to go terrible wrong. It is just not her, not her style, looks like she rolled out of bed in her pyjama.
She's very classic. She almost has a uniform: shift dresses, trouser suits, decent coats. Her attempts at high fashion aren't great (in fact, often disastrous), but if she had been queen in the 1950s, she would have topped the best dressed lists. If I had a say, I would bin Natan and Fabienne Delvigne (so many badly finished hats). Her clothes are always excellent quality and well fitted, even when they don't suit her.
My Mathilde fashion faves: