OK, thanks both. Next time I trundle round, probably this weekend, I'll save a profile of a single lap and post it. And thanks for the advice. As lazy as I am, my default position hitherto has been for my brain to scream "hey...this is hard...let's not kill ourselves" so this is going to be interesting.
EDIT:
No need to wait, I saved the ride when I was scoping out the course.
Here is the Strava segment. The only difference is that I close the loop in the NW corner in order to complete just over 10k and, as you'll infer, that last 0.6 km is uphill. Pay no attention to the time, this was an exploratory ride.
Wind is usually predominantly from the west.