Fascinating story!
http://www.naval-history.net/xGM-Chrono-01BB-Nelson.htm
SERVICE HISTORIES of ROYAL NAVY WARSHIPS in WORLD WAR 2
by Lt Cdr Geoffrey B Mason RN (Rtd) (c) 2003
HMS NELSON - Nelson-class 16in gun Battleship
May 18, 1941 At 0015 hours in 9.07S,04.42W,approximately 226 miles south of St Helena the raider ATLANTIS, which at the time was stationary, sighted two darkened vessels approaching at speed.
ATLANTIS identified them as warships and moved slowly out of their path. The vessels she sighted were NELSON and EAGLE, and they passed within 7000 metres of her without either vessel sighting ATLANTIS.
At 1100 hours arrived at St Helena to refuel. At 2345 hours following refuelling departed St Helena to proceed to Freetown in company with EAGLE.
It’s hard to believe that both warships passed as close as 7000 meters from Atlantis and the lookouts, and radar (I presume) entirely missed her. I’m wondering if she was sighted but the warships assumed she was an ordinary freighter.