Spiky,
No the Subtotal function has not changed in Excel 2007, it still
doesn't handle horizontal ranges (for the life of me I can't figure
out why they don't have this option).

Thanks for the suggestions, I don't have a problem with the manual
calc since the spreadsheet is set up that way anyway. I will look for
the external UDF and see if that works - otherwise, and unless someone
comes up with a better solution, I may just find myself having to
create an additional table where I transpose the data to a vertical
orientation and use Subtotal and then bring the value back to the
horizontal table. Rather a long way around what should be a fairly
easy problem to solve.

Your other suggestion using CELL is no-go, too many columns (over 50).

Again, thanks.