"Kevin McCartney" wrote...
So how come if you type an load of text into a cell, select half of it,
click
on the Bold button on the menu bar, press enter and half of the cell
contents
are in bold but the othe half are not. How does Excel do it?
....

No one is saying there's a good reason you can't do this in formulas, though
it'd require running the formatting engine after the recalculation engine if
it were possible.

In a nut shell, Excel provides access to the rich text Characters object for
cells containing literals, but it doesn't provide access to this class for
cells containing formulas. It's a design decision/limitation. Nothing can be
done to change it until Microsoft decides to reprogram it.