Saratoga gives Somerville a credible dawn follow-up

What changes if Somerville has USS Saratoga and her escorts during the Indian Ocean raid?

He is likely more aggressive and more willing to launch a night strike, knowing Saratoga can provide a dawn follow-up.

The added American carrier provides mass and a reserve strike rather than merely another flight deck. Somerville believed he faced four enemy carriers, so three Allied decks would give him something close to parity. He could commit the British air groups to the night attack for which they were trained. Saratoga would then retain a fresh daylight group for a dawn follow-up, making the initial gamble easier to accept.