Hi Kaye, I've had a look at your recent posting and it's difficult to work things out but here goes:-
Owen Williams, I've had a look at the photo copy of the Marriage Certificate and these are the details:-
Owen Williams' father was also called Owen Williams and was a coach man by trade but we don't know if his father was alive at the date of Owen's marriage
The witnesses were David Hughes and Anne Jones.
Owen and Mary's age was stated as 30 in 1859 on the day of the marriage, but this disagrees with the headstone on his grave which gives his birth at C1831 so there is 3 or years discrepancy between the two events we know about
I did find an Owen Williams in Mechel Anglesey in the 1851 Census and it gives his date of birth at about 1829. This person may or not be your Owen Williams as we have no evidence to prove it one way or another.
With regard to Owen Jones and Catherine Jones, do you know where Catherine was born as the weddings were normally carried out in the home Parish.
It may be that she wasn't from Llandudno and that's why I couldn't find a record of their marriage
By 1861 all of Owen & Catherine's children would have been old enough to have left home and that may be the reason why they are not on the 1861 Census. Sadly Catherine, Owen's wife may have died in the meantime and that may explain why she is not included on the Census.
Gaynor's age in the 1851 Census was 10 and Ellinor's age from Chris Draper's book was C1850 so there is a possibility of a mix up but looking back on my notes I can see when I copied the Baptism records down word for word it showed that Gaynor Jones was born 31st May 1839, she was then Baptised on 1st Sept 1839
Ellen, Owen Jones's daughter was Baptised on 13th May 1849 but the Baptism records show that she was 27 and a half years of age at her Baptism.
My theory, and that is all it is, is that Ellen's name was inadvertently shown as Ellinor in the book, but in fact the book should have said Gaynor as Gaynor's age matches the Census details whereas Ellen/ Ellinor does not.
Family research is interesting but can be frustrating too