This debate about middle aged or older women having long hair will always have split opinions. Simply because there is no right or wrong (or standard) solution for which hair length suits certain age or certain people. Jilly obviously likes herself with the hair as it is, otherwise, I am sure she would have changed it by now. We can all have our opinions on her hair, but it's her own opinion that matters.
I personally don't think she will look any better with shorter hair (neither I think she will look any younger sporting a shorter 'do'). Jilly has very much the same type of hair like mine - baby fine and poker straight. This type of hair is NOTORIOUS for not being able to hold any style at all. Trust me, I've been there. However you have it cut or styled, no matter what products you use, in 30-40 minutes it goes as flat as a pancake and as limp as a limp lettuce .
I never ever had a long hair before in my life, not even as a child. Then, five years ago, after the birth of my second child I just decided to grow it out of practical reasons, as I had no time to do school runs, take care of a my newborn and style a difficult head of hair, every morning. As my hair started to grow longer and longer people started complementing me on my hair (which has never happened to me before). Last year I had my third baby and again it has been a godsend not to have to bother with hairdos on a busy morning.
I guess I tick all the boxes that BurlyBear speaks of, in not the most complementary manner in his last post (i.e. mum doing the school run with a long hair, etc), but I don't think I look a mess, mumsy or even witchified as someone else suggested, earlier on. Here is my pic with my baby, taken 3 months ago, judge for yourself, if you wish. I also just turned 39 last week, so hardly a young girl,any more. But, I can honestly say that I have never looked better with such a minimal effort, than I do now with my hair being long, despite pushing 40. My husband also prefers my hair long, so even more reason not to change. If anything, I wish I grew it long, decades ago!