Vintage Sierra dress made in England

Vintage dress, tight fitted, blue and white My mom wore this for her engagement party about 30 years ago !! Imported from England Only wore it once for the day, PERFECT condition Past knee length Bought it for a lot of money at the time NOT A TRUE UK SIZE 12 IN TODAYS SIZING She was about a double zero size at the time compared to today’s sizing standards Fits more like an extra small