Use a PopUp instead of a drop down?
My mistake, I am not using a Drop-down, I am using a Pop-up because when I use a Drop-down menu it only shows the record ID.
But thanks for the suggestion.
Do you have "display values only from second field" selected?
Well, isn't this embarrassing? That's exactly the problem, I thought I had selected "display values only from second field".
Thanks again, you must shake your head at us newbies!