Just to close........I put the new formula in 3 columns of the actual worksheet. File size went from 16,376kb to 15,770kb.
There are 26 columns!
Not altered processing speed though (Not that I can determine). The whole work book is formulae. It's taking 1 to 2 seconds at each data entry at present. Don't really want to remove the automatic calculation just yet though. Will keep simplifying the formula's like this.
It doesn't seem to be computer power as the limitation of calculation speed. I am at home at present, with the file on a gamer spec machine (Significantly better CPU etc. than those at work), and the speed is hardly improved.