Unless she shaves her head, I cannot see how would any type of cut or different style help her roots and grey not to be visible, assuming she is still off colouring her hair for a moment.
Can anyone explain to me, seriously, why on this forum ANY hair longer than shoulder length is always seen as unattractive? What is wrong with clean, healthy, styled (and Kate's hair is styled, so is other princesses, always nice, fresh, clean and styled, no matter how long it is) and nice looking long hair?
Seriously nobody likes long hair anymore?
Any time there is any princess with hair slightly longer than her shoulder, there are voices saying "she needs a cut", "her hair is too long", "it's time to cut her hair"... etc. I think the only exception is Victoria, but it's probably because she never wears her hair open.