I have just come across your post regarding a French prisoner of war named 'Hubbard', buried down south, possibly from Norman Cross prison depot.
This sounds very as if it refers to Jean Marie Phillippe Habart, a French prisoner from Norman Cross who resided in the Stilton area after the war, and is buried in Stilton churchyard. My interest in him is from my specific interest in Napoleonic prisoners of war (I had a book published in 2008 entitled 'Hell Upon Water: Prisoners of War in Britain 1793-1815 that covers all the prisons including Norman Cross). I was also involved in the restoration of the Norman Cross Eagle Memorial, the monument that commemorates the 1,770 prisoners who died at the depot.
I am currently working on a book specifically about the prison at Norman Cross, and will include the story of Habart.
What I know so far is this. he was a French civilian, captured in a boat off Calais in 1803 and brought to Norman Cross as a pow. He worked as a baker in the depot, and during his time there met Elizabeth Snow, daughter of a farmer from Stilton, who delivered milk to the prison. When Habart was released in 1814 he went back to France, received an inheritance, and came back to England and married Elizabeth. They lived in Stilton and he set up a successful business as a baker and corn merchant (although he is listed as publican on the 1841 census). In 1846 he was returning from Peterborough when he was robbed and murdered. His gravestone is in the churchyard (I can send you a picture if you wish).
The 1841 census lists him as John Habart, married to Elizabeth, with Jane, Robert, Reuben, Elizabeth, Henry and James living with them. Elizabeth Habart was still living in Stilton (as a widow) in 1851.
This is all I know about him at the moment, but will be doing further research on him for my book. It would be interesting to learn when the family name changed to Hubbard, and if his descendents still live in Stilton today. If and when I uncover any further information I will let you know.
Hope this is of interest.