Adding the same header row to multiple spreadsheets

I was hoping to find a way to do this without using a macro, but I doubt this is possible, anyway I managed to do this in the meantime, Hans from Microsoft Answers kindly provided the code for the following macro which does just what I was asking for:

Sub SetHeaderRow()
  Dim strPath As String
  Dim strFile As String
  Dim wbk As Workbook
  Dim wsh As Worksheet
  ' Let user select a folder
  With Application.FileDialog(msoFileDialogFolderPicker)
    If .Show Then
      strPath = .SelectedItems(1)
    Else
      MsgBox "No folder selected", vbInformation
      Exit Sub
    End If
  End With
  Application.ScreenUpdating = False
  If Right(strPath, 1) <> "\" Then
    strPath = strPath & "\"
  End If
  ' Loop through the Excel workbooks in the folder
  strFile = Dir(strPath & "*.xls*")
  Do While strFile <> ""
    ' Open the workbook
    Set wbk = Workbooks.Open(Filename:=strPath & strFile, AddToMRU:=False)
    ' Loop through the worksheets in the workbook
    For Each wsh In wbk.Worksheets
      ' Insert row
      wsh.Range("A1").EntireRow.Insert
      ' Set some values
      wsh.Range("A1") = "This"
      wsh.Range("B1") = "That"
      ' ...
      wsh.Range("L1") = "Finally"
    Next wsh
    ' Save and close the workbook
    wbk.Close SaveChanges:=True
    ' On to the next
    strFile = Dir
  Loop
  Application.ScreenUpdating = True
End Sub

Thanks again Marcol, and again apologies for the cross-posting.