Lolly Doll is a fairly new repro brand. I ran a giveaway with them at Christmas on my sister site Retro Chick. They make some lovely looking pieces, and I’m particularly in love with the art deco collar on this pencil dress.
There’s no mention of length, and on the model they look around knee length, so if authenticity is important to you then you might want to check. The dresses can be custom made, so length might be something that could be changed.