Its interesting to remember that Pilates, now a hugely popular guide to posture was developed in the 1940's and named after Joseph Pilates.
Women of the 1940's simply had to master correct posture. There was no option.
Corset makers like Spencer did their bit to help, but there is no better alternative than simply learning how to stand, walk, and sit like a lady.
On our Youtube channel, Miss Ratherly Stern pops back in her time machine from the 1940's with her advice on good posture.
Her finishing school for girls is a good example of what was considered important for women then. As antiquated as it appears, it's always worth grabbing the useful advice that was dished out to young women in the 1940's, as they still apply when it comes to being glamourous.
Also do visit Gerties new Blog for better Sewing, for her take on this subject