I was surprised to notice the other day that the Clinique counter in the Army & Navy is staffed by young men. Your army & navy stores sell cosmetics? Must be popular with the Danish Venture Scouts. This is a significant north/south division. And by south , I mean the Home Counties. To me, an Army & Navy is a type of shop which sells camping equipment, outdoor clothing, boots, etc. Like a less tidy Millets. I think the southern Army & Navy is a department store. Lots of places now use the name, but the original was in Victoria Street, London; indeed its successor still is. See
http://www.archives.gla.ac.uk/collects/guides/armynavy.html for some of the history. It was London's first department store, and had a reputation as somewhere you could buy anything. Someone (it might have been Evelyn Waugh) suggested that a visit to the Army and Navy was the best way of convincing a foreigner of the superiority of the British Empire.