While I can't remember exact numbers off the top of my head, I do remember that the Taranto raid was even more successful in this timeline, so the Italian navy is in shape to set sail.So, the big difference with OTL Pearl Harbour raid is that the Hapanese have sunk an aircraft carrier besides the battleships (and as result they sufferd slightly more casualties). The loss of Lexington will be offset (partially) however by the presence of Ark Royal in the Pacific plus the survival of the 2 British battleships. I hope that leads the Amricans being lesscocky against the British...
Also, Ireland is not going to participate very actively in the war (at least at first) but the logistics for the Allied anti-submarine campaign will be much simpler with the usage of Irish ports and airports. I would like to see however an Irish brigade participate in the liberation of France!
Finally, ΗΝ Salamis the only active Allied battleship in the Med? That is a nice bargaining chip for Dragoumis (but also an eneormous pressure on the HN). How many Italian battleships are active at this time ITTL?
If I can remember, every battleship took some damage, but one of them was basically fully functional, but the other 2 would take months to fix up. Salamis can't take out that battleship by itself however, so it's not like it can properly contest the med without ground based air support.
I wonder what impact a much stronger Britain in the East will have. If they can prevent the fall of Singapore, then it basically cuts off the Japanese from Malaysia, Indonesia, Australia, etc. It would also do wonders for British morale, as the combined loss of Singapore and Hong Kong was an enormous hit both to domestic confidence, and colonial prestige, with many groups which were previously loyal-ish reconsidering when it was apparent that the UK was so weak. ITTL the UK is fighting actively all over, North Africa, greece, the Middle East, and Asia.
Historiographically, I imagine that greater emphasis would be placed on the UK's role compared to OTL, where they are often the forgotten third partner of the big three. France will also benefit, from the fighting French army serving so heroically after the fall. I don't know if these morale/prestige/legacy benefits will have any material good in the immediate postwar however.
I did read an incredibly detailed thread about the difference of the war ending in 1944 due to a normandy equivalent in 43, and how it would have major impacts on Britain's war debt, and ability to handle reconstruction.