Evenin chaps. Looking for help on finding out what H.Y.A.A. means! My Gramps was in the 395 H.Y.A.A in the Second World War and I think he might have been involved in Ack Ack. This is what I suspect the A.A. stands for, but what about the H.Y. ? Any help would be much appreciated. This post also posted in the history forum.