Thank you very much for this, John. We've had previous message contact over this family a year or so back.
I've been to the archives and had a look at the marriage and it's a widower marrying so I don't think it's right. I took a look at all the others I could find and the best match is Evan Roberts to Catharine Roberts at Capel Garmon 17/6/1837. Richard Jones and Catharine Roberts were witnesses.
If I remember correctly you were researching a line involving another Evan Roberts Ysbyty Ifan whose grandson (through daughter Dorothy) Richard Davies married a granddaughter of my Evan Roberts (Mary Ellen Morris, daughter of my Evan's daughter Margaret Roberts). I have now located a grave and photo of gravestone for Richard if it is of interest to you.
Thanks again for taking the trouble to reply.