This dress from Warehouse has a retro 1960's look to it. It looks like a top over a dress but it is all in one, the top is attached. The underneath top is a pretty lacy design, which can be seen at the back where it gently swings open.
96% Polyester 4% Elastane
Lace: 63% Cotton 35% Polyamide 2% Viscose
Lining: 100% Polyester