She's written a column for the Irish Times talking about the possibility of a sub-4 mile for women. What struck me however, was this parargraph.
In 66 years since that door was opened, over 1,500 male athletes have run a mile in less than four minutes; just 109 women have run 1,500m in less than four minutes. In terms of pure numbers a more realistic comparison would be a sub-4:34 mile for women, equating to a sub-4:14 for 1,500m.
I think what she's saying is that basically the same number of women have run under 4:34 in the women's mile as 4:00 for the men.