"Try as they might, the best fit they could get at Greenwich put the WGS84 meridian to the east of Airy by a tad under 102.5 meters. "

This is of course nonsense, since you can define 0 longitude to be on the Airy Prime meridian, no matter how you fit the earth. Ie, if there is a misfit, they must have used other criteria to define 0. What were those other criteria?