I do indeed have a copy of George Gurney's marriage certificate to Jane Hibbs from ancestry.com but never realized that the writing by William Gurney's name said deceased. I also hadn't thought to remember the witness' name, Boughton. Which, given the other information, should (hopefully) be related. Also, one of George's sons was named James B. Gurney. I wonder if he wasn't named for James Boughton....
Coincidentally, George's second marriage was to Jane's sister, Frances S. Hibbs in 1851. On the second marriage certificate, George's father's occupation is listed as carpenter but there are no Boughtons as witnesses.
The obituary for the grandson said "George Gurney [...]; son of William and Elizabeth (Boughton) Gurney". It also lists Frances Hibbs and her family, for whom I have documentation.
Where did you find William Gurney's burial record? I am working on English genealogy, but so far, am not too familiar with all of the websites etc.
Kati