How an Allied Italy changes naval deployment

How would an Allied Italy affect Germany and Japan in the Second World War?

Germany would face a vulnerable southern flank, while Britain could move much of its Mediterranean naval strength toward the Indian Ocean and Japan.

The counterfactual begins with Italy opposing Germany rather than joining the Axis. German troops committed against France and Norway would then have to account for an exposed southern frontier, potentially changing both campaigns. For the Royal Navy, the larger consequence is release from the historical Mediterranean struggle against the Italian fleet and the North African supply war. Ships no longer needed there could reinforce the Indian Ocean while remaining far enough west to avoid immediate Japanese attack. If Japan moved, that fleet could advance from a protected position, giving Britain a much stronger maritime response in the Far East.