I wish to format an existing sheet so that all negative values show in
red. This seems simple, but I have a few problems:-

1) Its a very large sheet and,
2) I can't format all ranges within a column as I have dates in some
rows which I wish to leave as is

How then could I format via code:-

So a negative value would shows as -1,234.56 (in red)
And a postive value would shows as 1,234.56 (in black)