Thanks guys that helps me a bit.

I changed the bit of code that was failing to:

importbook.Worksheets(1).Copy _
befo=mainbook.Worksheets(1)

mainbook.Worksheets(1).Cells.Copy
With mainbook.Worksheets(2).Cells
ActiveSheet.Paste
End With

but now it doesn't fail....sadly nor does it copy, if I try to
reference the worksheet directly is fails again.

What I want to do is just copy the cells from importbook.worksheets(1)
to a named worksheet in mainbook.

Can anyone help?
Thanks