England - how to know if an original record set from an archive is complete?

Question

I have been doing some family research and my research may suggest that some of my ancestors were from a small village called Thorganby in Yorkshire, England.

I have read the history of the village here: https://www.british-history.ac.uk/vch/yorks/east/vol3/pp112-120#fns

The article suggests that the primary church for the village was St. Helen's Church of England but there might have been a few non-conformist village members too.

I found the records from the church here: https://borthcat.york.ac.uk/index.php/pr-thorg They seem to be the original records created by the church at the time.

FindMyPast and FamilySearch both have claimed to index the records. https://www.familysearch.org/wiki/en/Thorganby,_Yorkshire_Genealogy

Questions:

1. Are the indexed images of the original records primary sources? How would I reference those?
2. How do I know if the original church records held at Borthwick Institute for Archives, University of York don't have any gaps?

Answer 1

What scheme are you using to assess your sources? A baptism record from a website would be considered Primary Derivative Direct according to Elizabeth Shown Mills assessment scheme which is widely used.

Re gaps, you can only rely on the coverage information from the various providers (and some testing because not all providers are entirely accurate about their coverage), and a comparison of the same, unless you are in a position to view the originals.You have to do the groundwork, basically.

For baptisms/christenings for example: the Borthwick Institute says:

Includes register of christenings, 1653-1885 (note this register uses the Dade registration scheme for the years 1792-1812)

whereas FamilySearch leads to a number of options from other providers (including FMP) which may or may not have some gaps, but you won't know until you assess them. You should not rely on what FS says but go to the providers they reference.

Genuki provides a useful crosscheck.