Old thread I know but I thought I'd add a few suggestions:
Veja trainers - French brand, v cool, eco-friendly and fair trade, soles made from wild rubber from the Amazon. Pay more than market price for organic cotton. Trainers produced in fairtrade certified factory where 80% of workers are union members. Can sometimes be found on Zalando at a discounted price.
Teko socks - high quality ecologically friendly sports socks. All socks made in Italy and transported via boat for lower emissions. Pays fair price for wool, labour etc. Uses recycled polyester. And the socks last ages!
Finisterre - men and women's 'performance wear' i.e. anoraks, base layers and wetsuits but also organic cotton tees, shirts and jeans - quite A.P.C. like in terms of styling. Clothes produced in Portugal and UK - fair wages and full transparency in supply chain. Merino wool all from British sheep. Can send anoraks back to be mended if necessary.
Swedish Stockings - Stockings made from recycled yarn in zero-waste, solar powered factories.
Nude Label underwear - ethically made in Spain.
The Acey - sustainable and ethical women's fashion. Chic, definitely not hippyish, and good for work wear.
Seasalt (Cornish brand) follow the ETI (Ethical Trading Initiative) and try to produce as much as possible in the UK. Also much of the cotton they use is organic.
None of the above brands are cheap, I know, but I am trying to buy only when I need and then to make the most ethical choice possible. Will add more as and when I think of them.