R.P. Williams
How does one mark a reference as questionable.  While I was able to find a blog mention of the "feat" of him running 9.0 , the person writing the blog was unnamed and gave reference to an out of print book "The Super Athletes" by David Willoughby, which I later tracked to being published in 1970.  Further that:  another reference to the book, commented on by Garry Hill, noted editor of Track and Field News responds "Willoughby's book, while a fascinating read about feats of strength, is, to say the least, largely the work of a guy given to wild flights of fantasy in comparing people across the ages. Very little science involved. Take it with many huge grains of salt."  Later in the same blog, he cites the unbelievability of this one mark as substance for such a statement.

I have not stepped out on a limb to delete the item entirely, but certainly more documentation, beyond even Willoughby to his original sources sounds appropriate here.