I'll just say Hamish, that having sold approximately 500 UK's myself in the last year most American men dont wear them anywhere near midcalf.

I think I may have sold less than a dozen that length total, and most were to younger boys who had quite a bit of growing to do and didnt want it to be too short in 6 months. (ever see a 16 year old grow?!)

By far most guys who buy a Utilikilt get them to fit somewhere between the top of the kneecap and the bottom of the kneecap. Rarely they will choose a bit longer or a bit shorter, but almost never more than an inch above or below.