Malcolm,
I cannot confirm that George was at Buckingham, though it looks like Charles was. If they were not related there is no reason George was there.
Millers I have in Brundish at this time were...Philpot, Green & Kemp (slightly earlier were a Mr. Cook & Randall).
I have check another milling db I have (not completed) on Baps in all Suffolk's parishes where father was a miller (1813 to about 1850 only) and have the following additional Vincents.
Palgrave 1851 Thomas & Emma Vincent (son Wm. & dau. Rosa)
Hadleigh 1838 James & Maria Vincent (dau. Maria)
Brundish 1829 George Vincent m. Charlotte Cook
Brundish 1831 George & Charlotte Vincent (son George)
Brundish 1832 George & Charlotte Vincent (dau. Maria)
Brundish 1834 George & Charlotte Vincent (son John)
Brundish 1838 George & Charlotte Vincent (dau. Hannah & Eliza)
Not sure if any of these are yours? If they are and you have any maiden names (marriage dates, etc.) then that would be excellent as millers tended to marry into the trade.
Cheers,
Windy