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For me an amateur this has me stumped but maybe someone more experienced can help out.  My great grandfather was William Hollis, born Etwall Derbyshire in 1853.  From his marriage certificate of 1882 I know his father was George Hollis, a joiner.  I recently got William's birth certificate in which his mother's name is Hannah Hollis but the boxes for the name of the father and father's profession are blank. I realise this could mean that William was illegitimate, but why would his mother Hannah register herself as Hannah Hollis if she wasn't married to George at the time? Or is there another reason why the father's boxes are blank?  Many thanks.

Mike