How Britain might answer operational Axis carriers

What could the Allies do if Germany and Italy both sortied carriers?

Britain would likely use Malta-based submarines to contain or sink the Italian carrier and organize a major task group against the German sortie.

Rather than immediately accept a carrier battle under Axis land-based air, Britain could station U-class submarines off the Italian carrier's operating port. Malta offered a base from which those boats could make the carrier their highest-priority target as soon as it sailed. This containment strategy avoided risking a British carrier force on terms favorable to the Regia Marina. A German carrier sortie outside the Mediterranean would instead be treated as a major fleet operation demanding a concentrated task group.