I was stationed in Germany for 2 1/2 years from 1981 to 1983 yet I was told as late as 2010 before I retired, similar to what you just said, that mad cow is forever.
Would like to learn more about the five year rule you cited. Is there a difference, epidemilogically speaking, between being stationed in U.K., & stationed in Germany?
The five year rule is general--applies to anyone who spent five years or more in any European country since Jan. 1, 1980.
You might Google "Red Cross Mad Cow" for their guidelines to see if you are excluded by their rules. It is not the same for all countries.
Of course people who have lived in Europe all their lives give blood to the Red Cross in their own countries...the Red Cross doesn't have to import blood from North America for the Europeans who need blood.