Rainer, remember this thread? [www.warsailors.com
Did you ever find any more about this attack? I'm beginning to wonder if it was indeed Thelma who was attacked by Marcello that day, for several reasons. I'm currently working on Convoy HG 20, and when I saw that the Commodore mentions that the straggling Thelma was reported to have been "torpedoed", I went back to the Norwegian book where I had previously found that piece of info about Thelma being attacked by artillery from Marcello. The time is given as 12:30 on Jan. 20-1941 in 50N 18 45W. She turned her aft end to the sub, defended herself with her own gun and arrived Oban undamaged on Jan. 25. My belief is that this would not have been mentioned in the book unless Thelma turned in an attack report. (It's also possible that she reported it to the Commodore, since he mentions it in his report, though he does not say so directly).
Rohwer gives the time of attack on Portugal as 12:20 that day, position 50N 19W. The Italian website about Marcello [www.regiamarina.net
] mentions only one attack, so I think we can safely rule out the possibility that they were both attacked(?).
I'd be interested in your thoughts on this. If you've found an alternative culprit for Portugal since you posted your intitial query, the matter becomes a little clearer, but if not, and if Thelma was indeed the victim of Marcello, the question remains, who sank Portugal? A couple of ships from this convoy were damaged by aircraft; for instance, the Commodore says the Greek Kapetan Stratos was bombed, and Mostyn is said to have been sunk, but this took place several days later.