Prior to the 1920s woman's bare neck and shoulders had been restricted to evening gowns.
Perhaps therefore in some ways extending the fashion to day wear was not as radical as other twenties fashions such as hairstyles and dress lengths
The scooped Bateau neckline is a classic twenties indicator. This open neckline allowed a woman to show her neck and shoulders during the day.The Bateau scooped neckline is the main feature allowing us to date dresses, blouses, knitwear and swimwear to the nineteen twenties.
Because of the neckline and cut of these garments whether they were knitted, crochet openwork or artificial silk; they required no fastenings.
They were by definition a " jumper" as worn by sailors and this may be one reason for the name bateau. Although beads and necklaces were worn, this neckline is frequently seen without jewellery.
Above date about 1923: Age about 19 years old Estimate: born 1904 ± 3 years