Wow! Found it. (And it WAS in an obscure, out-of-the-way location on my computer, too.) Ok, I was wrong about the thigh-highs and nobody looking at the camera, but I got the rest right.
Oddly, doing a reverse image search, I can find no other pics of this set or these girls. I know there ARE more pics, because I recently got (from here) a set of 16 B&W pics of these girls in this office. In those, most (but not all) of them look like they are having a party (playing with balloons and eating chocolates!
)
If anyone else can find any more color pics of this group, please post them here. Anyway, Here is the pic (you didn't think I was only going to TELL you I found it, did you?), along with two from the B&W set.