The unprecedented number of women MPs elected to the British House of Commons in 1997 provided an opportunity to examine the long-standing expectation that women would make a difference to Parliament once they were present in significant numbers. In both the 1997 and 2001 parliaments women MPs constituted 18 per cent of all MPs.1 Yet, as we have seen in Chapter 1, the concept of critical mass has been increasingly questioned, theoretically and empirically. So the story of women’s substantive representation by women MPs since 1997 was always likely to be more complicated than a straightforward and direct relationship between women’s descriptive and substantive representation.