Having not enough to do with my time, some would say, I did a quick poll from the censuses.
1841: out of 17 Neighbours, all were in Gloucestershire, and all but one born there
1851: out of 17 Neighbours, 15 were in Gloucestershire, 1 in Worcestershire, 1 in Surrey
1861: out of 23 Neighbours, 17 were in Gloucestershire, 1 in Staffordshire but born in Gloucestershire, 2 in Worcestershire, 1 in Herefordshire, 1 in Surrey, 1 in Sussex
1871: out of 21 Neighbours, 15 were in Gloucestershire, 4 in Worcestershire (2 of those being born in Gloucestershire), 1 in Berkshire but born in Gloucestershire, 1 in Kent
1881: out of 32 Neighbours, 19 were in Gloucestershire, 4 in Worcestershire (1 of those born in Gloucestershire), 2 in Herefordshire, 1 in Durham but born in Gloucestershire, 1 in Berkshire but born in Gloucestershire, 1 in Surrey but born in Worcestershire, 1 in Middlesex but born in Gloucestershire, 1 in Devon, 1 in Durham, 1 in Kent
1891: out of 9 Neighbours, 4 were in Gloucestershire, 4 in Worcestershire (2 of those born in Gloucestershire), 1 in Surrey
1901: out of 15 Neighbours, 9 were in Gloucestershire, 1 in Worcestershire, 1 in Herefordshire, 1 in London but born in Herefordshire, 1 in Durham, 1 in Kent, 1 in Middlesex.
So it seems if a Neighbour didn't live in Gloucestershire, he was probably born there or was from neighbouring (excuse the pun) counties Herefordshire or Worcestershire. Funnily enough the surname Neighbour was quite rare in Gloucestershire according to the censuses. Strange.
As for variations like Nabor – no, I really can't get started on that....
must do some work....