Great work. We really seem to be making progress.
The Burbidge /Reynoldes connection looks more and more convincing.I agree that it would be good to fit the witnesses in.
As you say, Petronella Harffy died unmarried in Enfield in 1796. She left everything to her niece Mary Coleman , wife of William Coleman of Enfield.
I haven't worked out exactly where this Mary fits in, presumably the daughter of another of Petronella's brothers. (The tree I am looking at and don't entirely trust shows sons Thomas b 1712 and John 1716 and daughters by their father’s first marriage, to a Mary Fairhead, but doesn't have their spouses or children.)
The Marlow /Marlham connection looks increasingly coherent too, but I am left with doubts. I could read Mary's name on her marriage as Marcham or Marlham; Marlow would be a push. And Mary and her siblings were christened in the City of London. This is the first mention I have of Vauxhall. Their son was buried in Southwark, their daughter in Kennington (probably not Kensington) and Mary's abode in her 2nd marriage was Newington - too many places. It would be worth checking the litigation that JJ mentioned when we have a moment.
Finally, in odd moments I have been looking for records of the apprenticeships that launched our Blunt sons as Chemists. (Paying for apprenticeships was one of the provisions of Robert's will.) Nothing yet, but I did find a Robert, son of William Blunt, apprenticed to William Robinson, an apothecary of Postsea, now Hampshire on 2nd May 1749. So perhaps there were already relatives on the business.
I also want to find out more about brother Richard Blunt and the Thomas Blunt of Petersfield mentioned in Robert's will.
Alan