How a British-Italian alliance would reshape the European war

How would the war develop if Britain and Italy were allied against France and Germany while Britain also fought Japan?

France would be badly outmatched at sea, Italy would be protected by Alpine geography, and Britain could turn Norway into the main European land campaign.

The proposed alliance structure is a deliberately artificial counterfactual rather than a claim about likely diplomacy. France would face the combined pressure of the Royal Navy and Regia Marina in the Mediterranean, while attacking Italy across the Alps would remain exceptionally difficult. Germany would likewise struggle to apply blitzkrieg methods across mountains or through neutral Switzerland. With no British Expeditionary Force committed to defend France, Britain could concentrate far more land, naval, and air power in Norway. Naval and aviation operations would shape the war from the outset in place of the historical campaign in northern France.