In article ,
Nick wrote:

Thanks very much for that...

You're very welcome!

In reality, the value 12 is unkown, it is found from an
INDEX/MATCH...

Replace the number 12 with a reference to the cell containing the
INDEX/MATCH formula. So, for example, if D2 contains the INDEX/MATCH
formula, replace...

=12

with

=D2

also the row A2 would be unknown when constructing the function.

Can you elaborate?