It’s an interesting question. Some things are ubiquitously both mumsy and frumpy, the bretton top for example. The Chelsea boot. The typical mum uniform that is now frumpy. And then we have the padded jackets. The floral dresses, white trainers, denim jackets.
to avoid it stay current, but something that suits your body shape. Wide legged or gentle flare jeans or trousers, , a midi dress or skirt, in.a good material, current colours and shape, that fits , an over sized cashmere jumper, a silk sleeveless top, an oversized chiffon blouse…for colours, muted , creams beiges, taupes currently, or all one colour, ie all navy or black, a fitted leather jacket, a good one, not biker, so many things, are current, of the 40 plus age range, and should be worn to suit the body shape. And quite frankly not dressing like a teen. As we get older quality counts, and we don’t need to spend a lot of money, vinted is a god send for it.
Clothes that fit, sadly I think weight has a lot to do with it, it’s hard to dress round the middle aged spread , for both men and women, hard but far from impossible, many achieve it
and good hair. a good cut, good condition, subtle make up, good shoes in good condition.