As it turns out, there are 2 ways to solve this problem:
1. Use a spreadsheet formula.
2. Use a VBA macro.

================================================== =======
1. The spreadsheet formula method checks the row above each County Name to
see
if it is either blank or the value "County Non-Migrants". If it is, then
copy the value of column C:D on the row to column A:B of the same row,
otherwise copy the value from the row above. Follow these steps:

1. Enter the following formula into cells $A$5:$B$17 (where each County Name
is listed in column $E):
=IF(OR(ISBLANK($E4),$E4="County Non-Migrants"),C5,A4)
2. Then Copy and Paste|Special Values to put the value back into these cells
and remove the formulas.

================================================== =======
2. The VBA macro method:

Public Sub CopyCDtoAB()
Dim ws As Worksheet
Dim rngStart As Range 'Starting County Name.
Dim rngEnd As Range 'End of data section at "County Non-Migrants".

Set ws = ActiveSheet
Set rngStart = ws.Cells(1, 5).End(xlDown)

Do
Set rngEnd = ws.Cells.Find(What:="County Non-Migrants", _
After:=rngStart, _
LookIn:=xlValues, _
LookAt:=xlWhole, _
SearchOrder:=xlByRows, _
SearchDirection:=xlNext, _
MatchCase:=False)
If (rngEnd Is Nothing) Then Exit Do
If (rngEnd.Row < rngStart.Row) Then Exit Do

'End of this section of data has been found.
'Copy values to columns $A and $B.
With ws
.Range(.Cells(rngStart.Row, 1), .Cells(rngEnd.Row, 1)).Value = _
.Cells(rngStart.Row, 3).Value
.Range(.Cells(rngStart.Row, 2), .Cells(rngEnd.Row, 2)).Value = _
.Cells(rngStart.Row, 4).Value
End With
Set rngStart = rngEnd.Offset(1, 0)
Loop
End Sub

--
Regards,
Bill