As it turned out, I managed considerably further than that.
It was still daylight, the streetlights hadn't yet come on, it was dry and, while no one could possibly say it was warm, the absence of wind meant that, compared with the past week or so, it felt relatively mild.
Started with my usual warm-up section but when I got to the end of my street, I decided to hang a right instead of the usual left and went off in the opposite direction. It did feel slightly strange running up hills I usually run down, and down hills I usually run up, but it was a change of scenery and a change of focus and, possibly most important, it wasn't cold, wet and dark and I could actually see what was around me; and that, I think, made all the difference.
In the end, I managed my third fastest 10k time of 1:06:05, so I'm not going to complain and, hopefully, I'm over my blip.