As we have seen before, surnames that originate in placenames can give us useful clues about the migration of people in the past. Contrary to popular myth, even in the medieval period there was considerable movement within the British Isles. In Cornwall, there are several surnames that are based on places to the east of the Tamar, sometimes many miles east.
One was Wellington, from the town in Somerset. This first appeared in the Cornish parish registers in 1590 when Elizabeth Wellington was baptised at Kilkhampton in the far north. At some point before the 1630s Wellingtons moved to mid-Cornwall. Later some went further west, but most were still to be found in mid-Cornwall around St Austell in 1861.
Sometimes, names from afar became uniquely Cornish and rare in other places. Oxnam, from the place called Oxenham in Devon, is an example. This was first noted at St Columb Major in 1572 when Richard Oxenham was buried. A couple of decades later the surname also turned up at St Germans to the east. This could have involved a move from St Columb or been the result of a separate move west from Devon. The spelling Oxnam was found from an early date along with Oxman, which may have been a misspelling of Oxnam – it turns up in the same district – or possibly another surname entirely which fell together with Oxnam.
Chesterfields came later and from much further away, presumably originating in the town of the same name in Derbyshire. The baptism of Henry Chesterfield and the burial of Elizabeth Chesterfield at Falmouth in 1709 hints at a maritime route to Cornwall. The name then quickly made an appearance in the St Ewe parish registers several miles to the east. It then ramified in mid-Cornwall. Whereas the surname died out in other places it flourished in its new home to become one of the more uniquely Cornish surnames by 1861.
Family historians may be able to qualify some of the broad-brush conclusions above gleaned from the aggregate data. If so, do let me know.