Hi Jack,
I'll probably get this wrong, but I think Fingest was in Bucks but is now in Oxon and Stokenchurch was in Oxon and is now in Bucks. it's very confusing. I just wish these bloomin politicians would stop moving county boundaries whenever it suits them - usually when they want to manipulate the votes in a particular constituency, no doubt!!
Did you say you were going to send for that death cert in Eton, hopefully the right John Goodwin? In an ideal world, the person registering the death will be Rebecca!!
It might be a good idea to send for that 1845 marriage cert of Rebecca and Henry Williamson in the hope that a) it's the right couple from all those names on the same page [use the referencing service] and b) to see what she gives as her maiden name. Again, ideal world, she'll be "late Goodwin, formerly Plumridge".
You never know, sometimes things do just come together!!
I'm glad you found that other Rebecca Plumridge from W Wycombe, as I found a marriage in W Wycombe on the IGI for a Rebecca Plumridge and Daniel Blick in 1827 and feared the worse.

Jill