stanmapstone - thanks.
I find this a fascinating topic and I do wonder how many illegitimate births were in fact registered as legitimate and further, given the alleged stigma attached, why so many were registered as illegitimate. I don't believe that people were more law abiding in the past (read the newspapers and Church Courts/Poor Law records etc) and would, if they thought they could get away with it, break the law to save face.
Maybe the widespread belief about fallen daughters being shown the door or bringing shame upon the family is wrong? Certainly the girls who had illegitimate children in my family were not and went on to marry and have families. They lived in small villages/towns so their past would not have been a secret.