Hi Martin

Visje is right :) (Rohwer does not mention the convoy WS-15 for Llangibby Castle, but I will add it)

The attack on Llangibby Castle was carried out in 46°04N/19°06W, thats about 600 miles northeast of the Azores and about 950 miles from Bordeaux, where the Fw200 bombers were stationed.
Their operational range was about 2400 miles, so Aagtekerk would have been in reach of the Focke-Wulf and the convoy WS-15 was formed on 12 Jan, 1942 in the North Channel, so everything fits your description.

Best regards
Rainer