Mike, Darwin writes about the seventh in 'The Golf Courses of the British Isles'. Park's original hole was blind on the approach as well as the drive; the green was much lower down and a long way to the left - it's now heavily wooded, but if you explore in the trees you can still find traces of it. Here's the quote:
"The seventh is a bone of contention, some averring that it is a fine 'sporting' hole, while others have no names too bad for it; when not alluded to with profanity it is generally known as the 'Switch-back' hole. Those who like a blind tee shot and a blind second will admire it, and those who don't won't, and there is the matter in a very small compass.
Colt moved the green to its present location, not long after Darwin wrote that (so around 1910-11). I think it is my joint favourite hole on the golf course, along with the twelfth.