Britain's Merchant Navy Carries On A Trip With A British Convoy - The constant watch. A Navy gunner scans the skies for raiding aircraft while on duty at his A.A. gun.In a confident, fighting speech, Mr. Winston Churchill tells us that while German ships lie idly rusting in harbor, Britain's world-wide trade is being carried on by some 4,000 vessels, 2,500 of which are constantly at sea. These pictures, taken by special permission, show how the Navy is making this possible despite the nebace of U-Boat and air attack. The photographer accompanied a Navy-protected convoy on a Northward bound journey. November 16, 1939. (Photo by London News Agency Photos Ltd.).