I've seen plenty of women at Dickens wearing them, presumably with Costume's approval. :)

I haven't seen any online examples of Heidi braids in period, but, as far as I can tell, any hairdo requiring long hair and PARTED IN THE MIDDLE (side partings for ladies aren't seen until the 1870's) is period. Heidi braids make sense for a shopgirl. They're easy do do for oneself and look neat and tidy, which would be a priority for the shop owner.

Well, I took a few glance through available resources (Godey's, Peterson's, Victorian photographs at www.cartes.freeuk.com/) and while I found a *few* examples of "Heidi" braids (center parted, simple side braided, braids pinned over top of head), I also saw a lot more examples of hairstyles that put the braids crossing on the nape of the neck or back of the head....or simply twisted up a bun or other hair binding on the back of the head so as allow it not ti interfere with a hat on the *top* of the head.

While I'd say that there certainly is evidence that there were people wearing their hair in the fashion you suggest in our time period, I think it was probably a less common alternative.