I have never seen this brand before and from conducting a little research, Topshop seems to be one of the few places that sells their stock. I would recommend having a look at this brand as it has a range of very cute dresses!
Here is what Topshop says about the brand:
It's a tale of two cities with Jones + Jones! Inspired by street style in London and opulent Southern France, these sisters have a flair for retro fashion with a modern twist. Think flirty skirts and bold fabrics mixed in with chic tailoring and add a dose of feminine cool to your wardrobe!
Here is the link if you want to have a look at their full range at Topshop Topshop - Jones and Jones and below are few of my favs :
Fabienne Dress By Jones and Jones
Lisette Dress by Jones and Jones
Sadie Dress by Jones and Jones