This latest post provided a few thoughts that had not occurred to me so I have done a little investigating. Unfortunately I have so far not been able to find any sign of Jane Tregurtha after the baptism of her last child so I cannot be absolutely certain of my conclusions. I searched for a burial that I had hoped might have recorded her age and in the absence of that I searched for a potential second marriage - unfortunately I was unable to find either.
In the absence of that information ................
The fact that Thomas and Jane Tregurtha named children William Bryant and Rosamond Bryant suggested that the mother was more likely to have been a daughter rather than grandaughter of William and Rosamond. The last child of Thomas and Jane Tregurtha was baptised in 1800 so it was possible Jane could have been born as early as 1752 so I checked the baptisms and burials again to see if perhaps 'Jannfer' had died young and another daughter baptised with a similar name. Having been able dismiss that possibility I refocussed on Zib's suggestion regarding the 1764 baptism of Jane the base daughter of Jane Bryant at Lelant.
Again focussing on the names 'William Bryant Tregurtha' and 'Rosamond Bryant Tregurtha' - I think the use of those names points to something more than the 'usual' grandparent to grandchild relationship. It suggests that much of the life of the grandchild was spent with those grandparents and that opens up two possibilities.
1. Grandaughter Jane (1764) was orphaned at a very young age and raised by her grandparents
In support of this possibility is the burial of 'a' Jane Bryant at Lelant 30th April 1768.
2. Daughter Jane (1734) married Charles Hocken in 1768 as suggested and, for whatever reason, her illegitimate daughter was left with William and Rosamond.
And in support of this possibility is the fact that the marriage was witnessed by 'a' William Bryant.
There are three marriages (two at Lelant and one at Phillack) involving a Bryant groom with a bride named Jane or Jenifer before 1764 and it is possible each of those marriages might have produced a daughter named Jane/Jenifer prior to the date of the burial above.
With a minimum of four candidates for the 1764 burial the chance of it having been the daughter of William and Rosamond is greatly reduced and therefore the possibility it was she who married Charles Hocken is enhanced.
Further investigation would be required to determine which of the above might be correct but I now think there can be little doubt that the wife of Thomas Tregurtha was the grandaughter of William and Rosamond Bryant and that she spent much of her life with them prior to her marriage.
CT