I am afraid that is the move. Get the glued on crimp with the left hand from the undercuts, build your feet on poor footholds and make a long move to the edge. Quite a hard one, took me longer than Flowers are for the Dead (which might get 7b+ now anyway).
Cheers John, glad we hadn't got it completely wrong!
I managed to throw past the slot on one attempt so all is not lost with that method! Thankfully the climbing up to that move doesn't seem too bad, shame the route is so damn sharp.
Hopefully it will be a first 7c for me soon!
Apparently Flowers is solid 7c now (used to be 7b+ in the guide).