Michael, thanks for those numbers. Really interesting! Can I just ask, do those calculations assume the standard pole-to-equator distance? I'm guessing so. The default is 100,000 isn't it?
I don't doubt your observations, but I was thinking that one degree warmer per 1000 blocks south seems like pretty rapid warming! If we assume that a temperate start is about midway between the pole and the equator (is it? anyone?) then that suggests that if you walked all the way to the equator from a normal starting position you'd get temperatures 50 degrees warmer than your starting point. I haven't spent a lot of time in the VS tropics but I don't think they're that warm are they?
Perhaps the warming function per kilometre south or north is a sigmoid: steep and linear around the temperate zone, and then levels off as you go north or south?
For anyone who has walked all the way to the poles or the equator, what sort of spring temperatures did you observe?