Fabulous floor length red satin dress!!

This was a gift and there are no tags, so I have no idea the brand or size. It fits like a 2. Front is floor length on me (I’m 5’9”), and back is even longer, with a bit of a train. The front has a knee-high slot for your left leg, but the folds of the dress make it a bit hidden. 61.5” from shoulder to front hem 70” to back hem 13.5” across the belt 16.5” across the underarms