At first I agreed with the above comments but if you zoom in the hardware seems too large on the center front to be a Birkin. There could be some kind of bag charm or junk on it, and it does look like there is a flap tucked into it. Good luck in your search!
I have a Dooney Priscilla in red leather that from the side looks nearly identical to this bag. Except for the side gathering strap. The Priscilla is rather Birkin-like and you can still find it on the Dooney web site. It's not vintage though. The style came out last summer.
About the "vintage" claim... A couple times I've contacted catalogs to inquire about shoes or bags in a picture, and it seems like they almost always tell me that they belong to the stylist and they're vintage--maybe so they don't have to admit that they're from someone else's recent line that the stylist may have snagged for free. So I've grown a bit skeptical when I hear "it's a vintage piece owned by the stylist." I can't help but think is it really?