From a terrace house near London's Olympic Stadium, a mother whispers her secret down the phone to me. She is speaking fast because she is afraid someone will come in before she has told me the shocking story of how she killed her unborn baby after an NHS hospital pregnancy scan revealed she was expecting a girl.
'I went to a private abortion clinic and lied that I could not cope with the baby because I was so young,' says 33-year-old Asha, a former bank clerk.
'I was panicking that I was going to have a girl because I knew my family wanted a boy. I was worried about her future growing up in my community that is still deeply hostile to girls. She would have to fight prejudice all her life, as I have done.'
Listening to her words, it is hard to believe they are being spoken by a British-born mother in the sophisticated capital of a modern, first-world country, where women have enjoyed the same voting rights as men since 1928.
Yet Asha, a Sikh whose parents came here from the Punjab, is telling me about a practice campaigners fear is worryingly common among some families living here originally from India, Pakistan, Afghanistan and Bangladesh. It has been discovered that the selective abortion of female foetuses (often with the unwitting connivance of the NHS) has provoked significant shifts in the natural sex-ratio of these migrant communities in favour of boys. Up to 4,700 unborn girls are estimated to have been deliberately aborted, following an analysis of the 2011 national census figures which revealed that in some areas of Britain, the proportion of boys born compared to girls is much higher than the natural rate.
