Some considerations on Italian neutrality:
1) The Brits have effectively more merchant tonnage from summer 1940 to mid-1943 because they can ship through the Med rather than having to around Africa. Big help in the naval tonnage war.
2) The Brits have considerably less actual merchant tonnage because they don't get to seize about a third of the Italian merchant marine that historically the Italians didn't get to safety in time.
3) The Brits don't lose the men and equipment that they historically lost in the attempt to rescue Greece and to defend Crete. Not sure where they use all of that, but presumably the men and material would be available if the Japanese tried something.
4) The Brits don't experience the Italian innovations in using frogmen against warships, and presumably are less likely to adopt them for use against the likes of the Tirpitz.
5) The Brits don't sink Italian battleships with a torpedo-bomber raid. The Japanese historically developed the concept of doing a similar raid on Pearl Harbor at least partly independently from the Brits, but seeing the concept actually work had to make accepting the risks of such a raid seem more palatable.
1) The Brits have effectively more merchant tonnage from summer 1940 to mid-1943 because they can ship through the Med rather than having to around Africa. Big help in the naval tonnage war.
2) The Brits have considerably less actual merchant tonnage because they don't get to seize about a third of the Italian merchant marine that historically the Italians didn't get to safety in time.
3) The Brits don't lose the men and equipment that they historically lost in the attempt to rescue Greece and to defend Crete. Not sure where they use all of that, but presumably the men and material would be available if the Japanese tried something.
4) The Brits don't experience the Italian innovations in using frogmen against warships, and presumably are less likely to adopt them for use against the likes of the Tirpitz.
5) The Brits don't sink Italian battleships with a torpedo-bomber raid. The Japanese historically developed the concept of doing a similar raid on Pearl Harbor at least partly independently from the Brits, but seeing the concept actually work had to make accepting the risks of such a raid seem more palatable.