Thanks for giving me a whole afternoons searching .I have been trying to find your man in my saved records that I have collected over the years.But I must admit to hitting the IGI web site quite a bit, also the FreeBDM one too!!.Well your man William, doesnt seem to be mentioned anywhere before his marriage to Agnes in the Dec quart 1875, I thought his birth might have been recorded as a GRAVENOR, or even a GROSVENOR, which sometimes happens!!, but no, so when I go up the city(Norwich) on Monday next, I will have a look at the BDM records in the city library to see if he is mentioned there!!A thought crossed my mind though, and that is, that the 'Twiss' connection, might have something to do with the naming of a father, in a illegitimate association, in fact there was a 'William Twiss' aged 26 living in Norwich at the same time!!! so that might be revelant.There again if you have William's marriage cert, it should have the name of his father on it, and checking the names on the census, there are only two Gravener familys in the Norfolk area, who could be his!! so we are in with a chance with them!!.I will let you know if I find anything next week.
Tony Grosvenor. Norfolk, UK ps. if you do have the cert, and there is an address, as to were he was living, I will go round there and take a photo of the place (if its still there) for you!!