In early April 1942 British Admiral Somerville, commander of the British Eastern Fleet, attempted to intercept the Japanese carrier strike force as they raided the Indian Ocean. British intelligence had told him where the Japanese would be going, but after waiting a few days, he decided the intelligence as wrong, and he abandoned his ambush just hours before the Japanese force arrived.
What if he had waited longer and been able to ambush the Japanese before they launched their strike against Ceylon on April 5?
Somerville had three carriers at his disposal - the HMS Indomitable, Fordmidable, and Hermes. The plan was to launch the British torpedo biplanes at night and be directed by their ASV naval radar. The Albacore would have been slaughtered during the daytime, but could have been quite effective at night. I'm not sure of the numbers, but I think Somerville would have had between 30-40 torpedo planes.
The Japanese expected to catch the remnants of the British fleet at anchor. They were surprised that the harbor of Colombo didn't have the British fleet in it. Instead, the fleet had either been moved to a newharbor at Addu Atoll, or was laying in wait. So it's likely that that the three British carriers would have caught the Japanese by surprise sometime after sunset. The Japanese had six carriers of their Kido Butai force present.
What would have happened if Sommerville's plan succeeded on April 4? How likely would he have damaged the Japanese carriers, and would it be enough that his own forces could escape? With confirmation that the Japanese carriers were found, could the British land based plans at Colombo be able to sortie and strike in the morning?
I find this intriguing because the battle could potentially be anything from complete disaster for the British to an earlier Midway style victory.