Guy,

This attack didn't sink a submarine, as there are no boat that went missing at that time.

I'll have to do a bit of additional research on this one to completely exclude all the German submarines in the area, but the British official history (Naval Staff Monograph, Vol. XVIII, pages 459-460) states that this attack was probably on the British submarine E 44 (!), which survived the attack. E 44 certainly did report being attacked by armed trawlers on that date.

Best wishes,
Michael