Here's my note under Fernhill on the F-page:

According to "Nortraships flåte" Freetown Radio received a radio message from Fernhill at 22:01 on Aug. 6 saying she was being attacked by a U-boat in the position given above. A Catalina was sent out and announced the next morning it had seen 5 lifeboats with 35 survivors. Rohwer says Fernhill was torpedoed on the 7th, position 06 58N 19 15W. The time given in "Lloyd's War Losses, Vol I" is 12:40 am GMT on Aug. 7, so this is very likely a matter of different time zones used in the various sources.

Siri