It appears to me that you are referring to the attack of 19 October 1940 (not 19 June 1940). WILK attacked a vessel described as a 2,000 ton merchant vessel in a position 4 miles south of Lister Light. She fired 3 torpedoes at a range of 4,000 yards but missed. The vessel was almost certainly the Norwegian steamer BETTY which reported avoiding 2 torpedoes on the same day near Lister.

Platon Alexiades
Montreal, CANADA