In reply to tingle:
https://www.ukclimbing.com/images/dbpage.php?id=69180&lgn=35691
Shows where the abseil off the Rognon landed us, and the climb from the col to the Plan summit.
Before you get to the top of the Rognon, there is a scramble gully/chimney down to the right, often with a rope in place. If you miss it, then you get the airy steps mentioned above, and a long abseil. Our abseil was a full length rope, and we shared with another team to tie our two ropes together to do it in one.
Fred (that's me in the picture)