The transcribed marriage register of St. Germans has no record of a 20 Dec 1772 marriage of John EASTLAKE and Jane ROBINS. Neither the Cornwall Family History Society nor the Cornwall OPC database have such a marriage, since they probably used this same volume. And I have finally tracked down what happened.

https://familysearch.org/ark:/61903/3:1:S3HT-65MX-16?cc=1769414&wc=3CBH-82S

 

So there was no marriage at St. Germans on 20 Dec 1772,which is why CFHS and OPC have no such marriage.

 

However, FindMyPast does show such a marriage, in transcript, at https://www.findmypast.com/transcript?id=R_844920391 which has no reference other than being from the FamilySearch index, where it is at https://www.familysearch.org/ark:/61903/1:1:NXJL-CQT which points to the image of the banns from the same typed St. Germans volume https://familysearch.org/ark:/61903/3:1:S3HT-65MJ-V5?cc=1769414&wc=3CBH-82 which shows the 20 Dec 1772 as the date of the last calling of banns but not the date of the marriage, since there is no record at St. Germans of the marriage.

 

In fact, the couple were married at Charles the Martyr in Plymouth 14 Nov 1773, which is seen on FindMyPast:

https://search.findmypast.com/record/browse?id=gbprs%2fply%2f004634464%2f00131

 

The answer lies in the banns at Charles the Martyr:

https://search.findmypast.com/record/browse?id=gbprs%2fply%2f004634452%2f00076

 

He was from St. Germans, and she was from Plymouth. The banns were called at both churches on the same three Sundays (6, 13, 20 Dec 1772).

 

They were married at Plymouth and not St. Germans, and the date of their marriage was 14 Nov 1773 and not 12 Dec 1772.