This ascent is on the Peaks of Lewisham Ride that Lewisham Cyclists run every year as an afterworker during Bike Week. Our ride was partly informed by an old sort of training ride I used to do three mornings a week before work many (many,many!) years ago, taking as many of SE London's hills as possible in about 15 miles or so.
And, last year, a young courier called Ben,(I think) got up the steep side of Canonbie, on fixed. And every other hill on that ride. And down every descent. Eyepopping (and thighpopping, for him,I would have thought).