But there literally was another carrier. They stated it openly flew the Union Jack too. It's not really a deception if there is real live carrier right there flying US planes.
It is if the Japanese believe the carrier is more powerful than it actually is. See my other reply.
Edit:
WRT the statement about the Union Jack, the jig would be up if the Japanese actually launched an air strike against the task force since the strike pilots would get close enough to clearly see what ship she actually was. Submarines and recon aircraft, however, would probably not be able to get that close and thus would just report a second, presumably American, carrier.
