The "Search the Online GRO Index" website has become one of my go-to sites for birth and death information in England. I realize the information given by the index is derivative and should serve as an interim source until more definitive evidence (i.e., the actual register) is obtained, but I would still like to cite it occasionally. Here's the format I've been using:
"Search the Online GRO Index," database, HM Passport Office (https://www.gro.gov.uk/gro/content/certificates/indexes_search.asp : accessed [date]), Joseph Caston, Mar qtr, 1847, Royston & Buntingford, vol. 6/491; citing General Register Office, Southport.
I'm using the Author/Title/Publisher/entry details format, but have left the author blank, since it is the General Register office.
Once I have received an unofficial PDF download of the document from the GRO, it seems to me that the PDF is now akin to an artifact in my possession, so I've been citing it like this:
England, General Register Office, death registration, Royston & Buntingford/Melbourn, 1847, no. 92, Joseph Casbon, 3 Mar; PDF copy in personal collection of Jon Casbon.
The image from the PDF is attached
I would appreciate comments/corrections. Thank you!