Plaid blouse dating?

[plousia]

Hi all, I found this lovely plaid blouse and am a bit lost as to the date, although I think it must be 50s or older. It's handmade; no pinking or serging, just unfinished seams. It did occur to me that it could be a child's dress, but I don't think that makes sense with the width of the collar and the pocket placement. Thanks in advance.

 

[Midge]

I'm wondering if this was a maternity piece, due to the cut... it kind of reminds me of this early 60s sewing pattern:

 

[plousia]

Oooh and they did a lot of Peter Pan collars in the 60s didn't they.... That would make sense.

Edit: although I'm not sure if that would be called a Peter Pan collar since it's not rounded?