I know this is lazy, but to save me having to spend time finding out how get
the name of the workbook to use in the definition, any chance you
could
supply me with the code?

The easiest way is probably to use the ThisWorkbook object.
Dim wksBLCK_Classified As Worksheet
Set wksBLCK_Classified = ThisWorkbook.Worksheets("BLCK
Classified")

Alternately, you can get the name using the ".name" property
debug.print ActiveWorkbook.name

or just
Dim MyWorkbook as Workbook
set MyWorkbook = ActiveWorkbook

Good luck