I munged the figures from last year's Abingdon marathon (up to mv50 & fv55) and percentage wise more women do get GFA times - e.g. 26% of male seniors vs 32 % of F seniors, 32% of mv40s vs 30-51% of fv35 & fv45s (it is a bit confused because the lines are drawn in different places to the gfa lines). 20% of mv50 vs 55% of fv55...
But numbers wise there are more than twice as many male seniors, about twice as many male middleaged runners, and almost five times as many mv50 as fv55 - when it comes to numbers who have made the grade.
Would be interesting to hear from the London organizers what their goals are with GFA...