Span v spun as the past of spin

I've been reading with interest the reactions to the latest Harry Potter book in which J.K. Rowling used "span" instead of the more usual "spun" as the past tense of "spin".
The US view is in accordance with their 1828 Webster dictionary: span is not used.
The British reactions were much more mixed. See the following comments from the same thread:
"I've never heard or seen (span as the past of spin) used in Britain"

"To my ear, "The car span out of control" sounds much better than the same with "spun"."
Question one. Why do some Britons deny that they've encountered "span" while others prefer to use it? Is there a north-south divide with "span" being used more in the north, less in the south?

Question two. What's special about "span out of control"? In Web searches, this phrase did appear more often than I expected relative to the same with "spun".
I carried out a word frequency survey on UK webpages and found that the overall frequency was:
8% span, 92% spun (excluding past participles e.g. the story was spun) However, the frequency for span/spun out of control came out as 22% span, 78% spun
The difference seems too large to be dismissed as a statistical fluke.