The first wave of 12 aircraft, led by Lieutenant Commander M.W. Williamson RN of 815 Squadron, left Illustrious just before 21:00 hours on 11 November 1940, followed by a second wave of nine about 90 minutes later. Of the second wave, one aircraft turned back with a problem with its auxiliary fuel tank, and one launched 20 minutes late, after requiring emergency repairs to damage following a minor taxiing accident, so only eight made it to the target.

The first wave, which consisted of six Swordfish armed with torpedoes and six with bombs, was split into two sections when three of the bombers and one torpedo bomber strayed from the main force while flying through thin clouds. The smaller group continued to Taranto independently. The main group approached the harbour at Mar Grande at 22:58


Source: https://en.wikipedia.org/wiki/Battle_of_Taranto#Attack