My grandmother Margaret Elizabeth Harrington was born 8/9/1905 in London. Have tried to trace her birth certificate through trawling the GRO index. Only one birth certificate matched. I purchased a copy, but found the actual birthdate and fathers name didn't match up. I know from her marriage certificate that her fathers name was Thomas Harrington. (She married John Hudson in October 1932 - he died in 1937, aged 37 years). How can I try to find her birth certificate, when very little is known about her early life? I have no idea of her mothers maiden name.