Hi Loolah ..... and Welcome back!!
Let's see if I can help you unravel this problem.
In the first place we need to take care of a discrepancy!
The discrepancy consists of two points -
1. up to and including 1837 there were but three marriages at St Ives involving Ann(e) Purefoy and one of these was way back in 1720 when John BROWN and Anne Purefoy were married!
2. I can find no marriage anywhere in the OPC database in 1770 or any other year between a Thomas Brey (Bray?) and Ann Purefoy. Even searching on 'Tho Br' married 'Ann P' produced no result so I need to ask just where that information might have originated.
AHA! - The record in 1770 I have just discovered was actually only Banns between Thomas BERRY, a soldier, and Ann Purefoy read at St Ives. I can find no record of this marriage having ever taken place.
The next thing we need to do is look at the marriage of James Berriman and Ann Purefoy in 1773. Looking at an image of the original register shows that in this case Ann Purefoy was certainly a widow. Yes, it would not be unheard of for her to have been recorded under her maiden name for this marriage even though also being recorded as a widow but it would have been unusual. However it can be easily proved that she was indeed the widow of a Purefoy.
A check of the Marriage Index for St Ives shows that a William Purefoy married Ann Watty in 1766. That in itself proves nothing ..... but a look at the image of that marriage alongside the marriage of James Young certainly does!
William Purefoy, mariner, and Ann WATTY, spinster, both of St Ives were married at St Ives 19th August 1766 with witnesses John Purefoy and John Care
James Berriman, carpenter, and Ann Purefoy, widow, both of St Ives were married at St Ives 16th February 1773 with witnesses John Purefoy and Thomas Berriman
In both marriages the bride and groom were both able to sign their own names and the signiatures of the bride in both records indicate Ann Watty and widowed Ann Purefoy were one and the same person!
I should also mention that I have only three children for William and Ann Purefoy baptized Ann 1767, Eleanor 1768 and William 1770. And just to further identify that we have the correct person I will elaborate a little more on Ann Watty.
Ann daughter of Thomas and Elanor Watty was baptized at St Ives 8th May 1747. I don't yet know the identity of William Purefoy but I suspect he was probably baptized at St Ives 25th June 1743 along with twin brother Richard - sons of John and Mary Purefoy. This then identifies the John Purefoy witnessing his marriage and it also gives us origins for the names of his three children.
Ann Berriman of St Ives age 80 was buried at St Ives 26th January 1827 - this also matches very closely with the baptism of Ann Watty in 1747 so I think we can safely remove the James Berriman marriage from your scenario.
Before further comment on the primary dilemma I need to point out something about the rumoured death of James Young in 1772. Firstly we have the baptism of his son James at St Ives in July 1772 but more importantly we have the burial of a Peter Young at St Ives in March 1831 at the age of 57. This puts his birth at about 1773 and I believe we also had reason to suspect that he also was a son of James and Ann. If Peter was indeed another son of James then he was either born posthumously or the suggestion of a 1772 demise for James is incorrect.
Now back to the dilemma. There is ample evidence in the above that none of the Ann Purefoy marriages at St Ives are connected and it also appears that the Banns for Thomas Berry and Ann Purefoy did not culminate in a marriage and that brings us to one very interesting point. Having checked both the OPC database and FamilySearch it would appear that there was but ONE Ann Purefoy baptized in all of England between 1720 and 1760!!
Ann daughter of John and Jane Purefoy baptized 5th July 1749 at St IvesJohn Purefoy and Jane Try were married at St Ives in 1743 and their first child was son Thomas who was baptized and buried in 1744. There appear to have been no other children except for Ann in 1749 and there is little chance she would have been born much before her baptism - certainly not before the marriage of her parents. There is also no evidence to suggest that she might have been an illegitimate child of Jane Try and then baptized as a Purefoy much later. That leaves me with two questions:-
1. Is this the Ann Purefoy who was to marry Thomas Berry?
2. Is the age of 81 as recorded in the burial register for Ann Purefoy in 1819 actually correct?
With so few Purefoy baptisms in Cornwall (and only one Ann in all of England between 1720 and 1760) I begin to suspect the possibility that this Ann Purefoy baptized in 1749 might actually have become the wife of James Young.
Consider this - Banns for the marriage of Thomas Berry and Ann Purefoy were published at St Ives in November and December 1770 yet the marriage seems to have never taken place. This may have been because Thomas died or for some other reason departed the scene although there is no burial for him at St Ives.
I can find no possible burial for Ann Purefoy either so after the departure of Thomas could she have then married James Young?
It is interesting to note that Thomas Berry and James Young were both soldiers!
If the Ann Purefoy in both cases is the same person and no burial for an Ann Purefoy can be found then it stands to reason that she would logically have to be the daughter of John Purefoy and Jane Try baptized at St Ives in 1749. It also stands to reason, given the paucity of Purefoys and Youngs at the time, that the 1819 burial at St Ives of Ann Young surely must have been the widow of James Young. And that then brings me back to the question of accuracy regarding the age recorded in the Parish Register for that 1819 burial!
I have noticed something very interesting with that Parish Register entry! Looking at the image which shows pages 44 and 45 of this register it is quite noticeable that all entries are written in the same hand and signed by 'Rob: Peter, Curate'. It is also noticeable that the handwriting is quite consistent and quite firm on every entry on the two pages ................ EXCEPT for one item!!!
The exception is that the age of 81 written in the entry for the burial of Ann Young is
written in a different hand and obviously with a different pen/pencil!!! I would venture to suggest the accuracy of the entry might well be brought into question!!
I am also now prepared to suggest the strong possibility that the burial age for Ann Young might well be recorded in correctly and that it therefore also a strong possibility that she was the daughter of John and Jane Purefoy baptized in 1749.
CT
). I need to untwist my preverbials!
) discovered eons ago that that marriage entry recorded Ann as a spinster. However, looking today at the OPC, I now see her recorded as a widow. BUT, even as a widow of just one year, would she not have been recorded as Ann Young and not Ann Purefoy? (I know in some cases widows reverted to their maiden names.) Or could this lady have been the widow of Thomas Brey? Or, more likely, the widow of a Mr Purefoy!!!
Let's see if I can help you unravel this problem. 
I hope you will be able to find a clue to some of that information so that your James Young can be identified.
