Where can you find information about The Great Brotherhood of the FBI which was probably associated with time spent in Iceland around June 8 1943?

Hi I cant answer the question, but while looking through a bunch of my grandads old stuff I found a (hand written) certificate from the "Brotherhood of the F.B.I" from 10th June 1943, i has a couple of signature on the back and also the the captain of the ships signature

I also have a certificate belonging to my father who was in the Royal Navy and stationed in Iceland from 21 November 1941 until 24 January 1943 on HMS Barbridge. He received the certificate having "endured the requisite period of 365 and one days or longer in the domain of and waters adjacent to Iceland". My mother told me this meant he had been granted the freedom of the Icelandic waters for life.