Thank you for the link.
I have followed the example but I cannot seem to get it to work.
Here is an example of what I have done
Book1 contains the range called List
Book2 is where I want to use it in a validation list.
First I created a defined name (in Book2) called Book2List with the range
name
=Book1.xls!List
Then in Data/Validation the source is =Book2List
I am obviously overlooking something but I cannot put my finger on it.