Yes, this was intentionally tricky, and I'm surprised that The Vintage Vortex actually got it right. Hopefully she will pop in to let us all know how she knew it.
It just amazing how different the skirt looks in the correct context, with the right shoes and the natural waistline and the hair and make-up of the period. But doesn't it still look strange? We just do not think of this length as being around in the 1950s.
It's pretty obvious that this never caught on. The editors of Mademoiselle must have really liked the look to put it on the cover of their College Issue. Here's what they have to say about it:
This is the Bermuda skirt, a flared flannel fling that's the same length as Bermuda shorts.
Bermuda skirt (ber- mu da skurt),n. 1. A short, shaped, knee-top skirt to be worn on campuses where shorts are legal. 2. A substitute for shorts demanding less in the way of an All-american-Girl figure.
But I can see why so many of you thought 1960s; my guess would have probably been 1964 or 65. I grew up here in the fashion back-water of America, and this look was big around 1968, and I figure we were about 4 years behind in fashion.
And even in the 1970s, girls at my school were still doing the skirts and knee socks thing.
I'm glad Jonathan made his post because I was hoping someone would reference the skiing skirt that had its moment in the sartorial sun in the late 30s and into the 40s. It too was wool and was this length. The skiier wore heavy wool tights beneath.
Thanks for all the thoughtful replies!