Number 2 wanted to know who Number 6 was signalling to. He checked with radar, but there was nothing at sea, no ship. He's shocked and puzzled by that, but surely there must be an aircraft, helicopter, something. But there's nothing! Under the sea, submarine, try the sonar.............. "No sir, there's nothing coming through." But he must be signalling to someone. Well he was, and I'd have thought that was blindingly obvious........ to everyone but Number 2!