Karen,
Yes, I do believe that William CORNWELL, the husband of Sarah (BLACKLOCK), was that returned from Barnwell for burial at Fulbourn (SV) on 31 Aug 1743. Along with Christopher Ruff, his brother-in-law, he was a trustee of Richard Wright's Clock Land, an endowment for the maintenance & repair of the clock, bells & steeple of St Vigor's Church and as such, he is named in a lease/release of land dated 26/27 November 1735. He was assessed for Fulbourn rates on 29 Aug 1738 and, on 6 Dec the same year, he received a 'constable's rate' of 7/9d from the Geoffrey Bishop's Charity at All Saints, Fulbourn. On 29 Nov 1741, the same charity also paid him an 'overseer's rate' of 11/4d. Significantly, he does not appear as a 'surviving trustee' on the next feoffment of land for Richard Wright's Clock Land dated 7 April 1755, which suggests to me that it was indeed him buried in 1743.
You have the advantage of me with the death of Sarah SCOTT in 1781. I have no note of this so details would be most welcome. I have her birth as c.1714 and (BLAKLOCK) baptism on 26 Feb 1714 at Newport Pagnall, Bucks., the daughter of Andrew BLACKLOCK & Mary (BOLTON). We already knew that her family held land there so this seems safe enough although her exact origins start to look increasingly complicated. Thanks for the blog link. It is highly plausible that Nelson BLACKLOCK ‘did a runner’ into the RN under an assumed name but I have no knowledge of any Scottish origins for his family.
Neither do I know of any children to William CORNWELL & Elizabeth (TYRELL). He was first cousin once removed to the William who married Sarah BLACKLOCK and their lines converge with John CORNEWELL (1658-1718) of Fulbourn - my six-times Great Uncle.
For sure, things would have been difficult for Sarah following the death of William in 1743 with three (or four?) children to raise. But only two of them were still babies, she was fairly comfortably placed, with good family support network on hand, so the three years until her second marriage could have been far worse. I think it unlikely that the CORNWELL grandparents were directly involved in raising the children as grand-father Richard had died ten years earlier.
Unfortunately, I can offer no guidance on any possible connection between Dry Drayton and Magdalene College, Cambridge. Quite a poser.