For me mumsy describes clothes that are flouncy and don't fit with the lifestyle of the person. Pussy bows spring to mind, and like someone who spends all day at the coal face of weaning, but gets an outfit from marks and Spencer's with too many fru fru embellishments to go to a wedding.
Frumpy otoh is when clothes look like they are badly fitting, too long in the body, and the wrong shape for your own body shape.
Those who have large norks who wear tunics and look square for eg, I think of as frumpy. (I have massive norks myself, so I "nork watch", and see what looks good on those similarly aflicted blessed, iykwim)
Dressing to your
body shape, and height
within budget,
in fabrics that suit (dry clean only can be a thing of the past), and no-stretch tailoring can be impractical,
for a lifestyle that you own,
with a little bit of flair,
in colours that enhance your best features (easy on prints and florals)
is stylish,
no matter what you do all day, how much money you have at the moment, or whatever age.
Angelina jolies dress looked a bit frumpy to me because it had a too long sleeve, mesh panels in a wide lampshade look around her face, and a terrible waist - it made her hips look square topped.
I get that she's changed, and her new direction of being a director / ambassador/ someone who has had surgery because of female health issues informs her look now.
I thought her choice was brave though considering how everyone was going on about her new boobs etc and what would she wear to show them off.
I think she dressed gracefully for her new sense of self, even though her dress was a bit of a frumpy camouflage job, she pulled it off - and she definitely wasn't frumpy or mumsy in the tux.
I think her transition after she has her ovaries and ?womb removed will be interesting to watch as we are all heading towards menopause, and I suppose we watch her as a style leader. I wish her all the best btw, and anyone who is going through such a radical operation.