Larry,
Surely the code encompasses the country code as well e.g. GB 10 2 (Aberdeen Dyce)
You had me a little worried there so I searched for some items on-line and found this
http://canmore-pdf.rcahms.gov.uk/wp/00/WP003869.pdf
Page 13 is a target photo of Aberdeen Dyce. Pg 15 gives GB 10 906 as Peterhead.