One of the joys of family history research is that when you answer one question several new questions immediately present themselves.
Last October I gave Carolyn some advice about the Ashby/Sherman family of Aldbury and Northchurch (part of Berkhamsted) and she has now sent me details of the marriage certificate. It appears that, having already got quite a large family they decided it was about time they got married. Obviously there would be people around who would be concerned about the souls of this couple who were "living in sin." Was a Christmas Day marriage - perhaps involving other wayward couples - part of a recruitment drive by the local Baptist Minister to enlarge his congregation? While I have not done so, it might be worth looking at adjacent entries in the Chapel register to see if others were married at the same time. Were the earlier children already baptised prior to the wedding - perhaps by the Church of England - perhaps at Aldbury? For full details of the research so far see Ashby/Sherman, Aldbury 1840/1851.