Yes because they have used what they had effectively and have other large naval presences. For instance a 7 strong destroyer fleet and haven broken through China, Russia and India… It has been a pain to be sure.
Just allow defenders to retreat after first round of battle like the attackers can do. That’s one of the rules of axis and allies that don’t make sense to me, defenders can’t retreat. If they are surrounded, I can understand they must make a last stand however.
What stops US or UK placing 4-5 fighters in Gibraltar. Each would roll a 2 vs a 1 the escorting fighters if any(lack range i think) might get. Each Bombing raid would cost the attacker 1-2 bombers from defending fighters before you roll AA.