Sailor suits for children from the 20th century in the special exhibition Klæder skaber børn (Clothes make children) in the museum Tidens Samling (Collection of the time) in Odense in Denmark. The red color is somewhat usual for such a dress.
<a href="//commons.wikimedia.org/wiki/User:Dannebrog_Spy" title="User:Dannebrog Spy">Leif Jørgensen</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>