Thanks so much everyone for all the links. I feel really ungrateful but none of then are quite doing it for me, not even the lovely pink Finery one or the Joseph aubergine. Part of the problem is, I can't work out why I like that Arket one so much. I don't even wear dresses very often these days and there are so many things about it - black, floppy fabric, bad sleeves - that should rule it out straight away. But it was an eyes across a crowded room, Omar-Sharif-spots-Julie-Christie moment.
In another sign I'm losing the plot, I'm also slightly obsessed with this from Toast. It's a jumpsuit, it's linen, it'll make my arse look bigger than China, it's sleeveless, it's two hundred quid. And yet here I am. Maybe I'm having a late life (it can't be midlife) crisis and the next time I post I'll have bought a sports car.