Good call Graham. Old age already biting deep here.
If you are going to include spaces then it will probably find spaces between lower case letters too. Assuming there are no double spaces in the document, you might ask the find to only return hits with at least two or three found characters
Code:
.Text = "[A-Z ]{2,}"
or
.Text = "[A-Z ]{3,}"
I would probably expand this to a minimum of three characters to avoid words that have an initial cap preceded by a space unless this is what the OP really wanted.