Indeed, this becomes more confusing because back in the 60s - in England, at least - what we now call "pattern playing" - was referred to as claw-hammer.
I think UK guitar players picked up the style from Ramblin' Jack Elliott who visited the UK in the late 50s.
By the early/mid-60s Joan Baez, Bob Dylan etc were using it lots!
In the UK, even staunch traditionist Martin Carthy used it!
I think Bert Jansch's take on it was beautiful ( Needle of Death, and Running from Home, for example).