The Clyde Variation (3rd or 4th class) starts VERY close to the base of the main 5th class chimney in the U-Notch. If you're descending the route, then note that the top of it is exactly at the top of the 4th class chimney. I've mistakenly looked for the route too far down the side of the ridge before, and there's nothing easy over there (it was sketch 4th and 5th class). Done properly, the Clyde Variation is very quick.

I have two other beta photos on this route:
image 1,
image 2