30 years ago the Conservatives had a clear lead amongst women voters, but that lead has steadily declined ever since. Labour last year had an overall lead of 6%.
Why?
Partly it is age. The Conservatives had a lead of 7% amongst the women over 55. But in the age groups 18-24 and 25-34 Labour had leads of 21% and 22%.
Partly it is social class. Although, as you would expect, Conservatives still had a lead in the richer classes (technically the ABC1s), it had been falling, and could not offset Labour's lead in every other group.
A likely reason for this is that women's political priorities are different from men's. Far more than men, women put education and the NHS at the top.
So now we can see why Cameron is laying so much emphasis on health and education as part of the Tory turnabout. He appears to be having some success. The Labour lead amongst women voters is falling.
On the other hand his success may be limited, because of the tendency in western nations for the women's vote to move slightly towards the left.