I have just found the most amazing visor sunglasses. They are by Bless and are available at farfetch.com. Unfortunately they are all sold out...I can't believe I missed the boat on this one. I've been saying all spring that I'm actually going to invest in a pair of decent sunglasses this summer, rather than spending a measly £15 on a pair from Topshop that I will probably sit on, chew or lose! These are only £188, which I know sounds a lot, but in the grand scheme of life it's not that big a deal (I am starting to loosen the purse-strings a little recently, well in theory at least).
They are a little avant-garde and wouldn't look out of place on Jean Paul Paula, but if I was feeling brave enough I could get away with them;) .