Hi,
My 4th great grandmother was called Eleanor Dimmock, I don't know much about her, but she married in about 1816 in London, to Isaac Seggins, he was from Norfolk and they had their family in Bucks, which leads me to believe that this is where she was also from.
The family were living in Weston Underwood, I need to consult the Bucks FHS when I can, this is one side that needs chasing up, but I am very certain that my Dimmocks came from Bucks.