Sarah : thank you for the tip & information. As suggested I have spent some time looking for John & Ann in the census records.
For some reason 1841 did not turn up anything useful, but in 1851 I did manage to find a John (70, B.Holywell), & Ann (71, B.Ysgeifiog).
So whilst there is a match on names / locations, and ages are about right, we obviously have no resident children to cross-reference. One assumes that if this Ann were from Ysgeifiog you would have identified a record of the marriage, on the basis it would have been customary to marry in her parish church..... I guess the marriage event would have been in the range of 1800-1808.... but I wonder where?.....
Chris