Hi Arnie - good interview on the other thread!
Yes, I am very aware of the WMA age-grading system, and parkrun issues a Grading score as part of the weekly results which allows girls & boys of different ages to see just where they really stand as athletes in a diverse pool.
My best historic performances (63:20 10 miles, 1:23 half, 2:54 marathon) all sit around 73 - 74%, my best halves as a 59 year old were just under 1:38, for the same percentage near as dammit. Never been a sprinter, fastest 400m was about 65 seconds, but fastest mile was about 5:20 - same as you. I seem to have aged along the appropriate curve, despite a few missing years of relative inactivity, such that I should expect to be able to hit 73% still - which means a 23 minute 5k! Stuck above 24 mins at the moment but working on it...
Yes, 2:01 now is better than 1:58 four years ago, especially that was racing and the recent run was jogging! Aiming for sub-1:50 if I do race another half...
Cheers, Pete (just turned 65)...