Favourite Jack Johnson story? “The speeding ticket,” grins Israel Adesanya, recalling that time in the early 1900s when Johnson, having not long become the world’s first black heavyweight boxing champion, was pulled over by a Philadelphia cop. Then on the spot, issued a $50 fine. To which, and without pause, the fighter withdrew from his custom trouser pocket $100, back then a monster wad, while explaining to the dumbfounded officer how not only would he be coming back along this same stretch of road later in the day but, well, he planned to be going exactly the same speed. “Which,”...