Button vs team-mates in Championship:
I think it is perfectly reasonable to say that the world champion remains as number one in the championship until the first race of the following season. I've certainly never seen anyone listed as 0th.
Not at all, the reigning champion is simply the championship leader when the number of races remaining equals zero. I see no difficulty in charting a driver's championship position continuously over time, since championship position varies continuously over time.That is because there are no results at the beginning of the season. There is also a big difference between being the reigning world champion and leading the current championship. These are two completely different things.
Back to the other discussion, are we now agreed that nobody turns up to a championship leading it before it has even begun? I