Thanks a lot Frank. As an FYI, I posted this question on another site and received the following script which also works. I have over 300 books to copy the script into. Such fun.
Private Sub Worksheet_Change(ByVal Target As Range)
Dim rg As Range, Cel As Range, cel1 As Range
Dim strFormat As String
Application.Volatile True
Set rg = Intersect(Target, Range("G6:G6")) 'checks if the cell In column C is changed
If rg Is Nothing Then Exit Sub 'checks if the value is not empty
For Each Cel In rg.Cells
If Cel.Value <> "" Then
Cel.Offset(-1, 0).Value = Now() 'places the current date into it
End If
Next Cel
End Sub