Very rudely, two years ago, I omitted to thank Bedfordshire Boy for his magnificent input. It should have fired me into full burn: unfortunately, like Philip Larkin, I had the "toad Work squat[ting] on my life".
Ignoring the various siblings and collaterals I have sniffed at along the way, the following sums up what I now have, over six generations. Again, I appeal to all-and-sundry for correction or confirmation. All offerings gladly received.
To make things explicit, let me start at the end of my Pigot line. Edward Wilson Pigot (the father my mother never knew) is one of the 1800 in the care of the CWGC at Doullens, on the Somme. He was born 1887, son of Matthew Tempest Piggott (1858-1932) and Susannah Wilson -- which is where this thread started.
The next up-the-line is Tempest [Piggott] Docwra, as Bedfordshire Boy acutely noted. The 1881 Census has a wife, Mary A, born 1818-9. As far as I can determine, the reversion to "Piggott" as a surname came with Tempest removing from Guilden Morden to Wisbech St Mary.
A further generation back is Rowland Piggot Docwra (1789-1863) and his wife, Mary Farmington (born c.1794). Sticking with the Piggot Docwras, the previous generation is Robert Piggot Docwra (1768-1807) and Henrietta Sell. The Sells feature on the Bassingbourn register, well back into the early 1700s.
Then comes the "indiscretion" between Robert Rowland Lacey Piggott and Elizabeth Docwra.
http://www.docwras.org.uk/doc-r.htm has the christening of their son Robert Piggott Docwra at Bassingbourn on 8 Apr 1782. IGI has his birth date as 1768: apart from one crytic note added to a citation of the christening ("age 14"), I have no more.
And that is where I currently am. To repeat: all comments and any brick-bats accepted, provided they move this thing along.