... the Pill might be causing thrombosis. With some difficulty I organized a national study, picking out all deaths within the childbearing age group that would occur in 1966. I had to wait for them to occur and follow them up. By that time I had recruited a team of field workers – we called them Derrick’s Dolls – they were personable, mostly young, doctors who visited the general practitioners to get the information at first hand, which the doctors appreciated. We got the cause of death from death certificates, and I used the same team to follow up the yellow card reports.