You might find a little more on these links.
http://www.rafcommands.com/forum/sho...-for-Finn-Buch
http://www.polishsquadronsremembered...315Losses.html
In the book "RAF Mustang and Thunderbolt Aces" by Andrew Thomas, on pages 37 -38 he writes:
"The strike squadrons that Coastal Command employed interdicting shipping of the coasts of Occupied Europe had done so largely unescorted, and had suffered significant losses to enemy fighters as a result, especially off the coasts of Norway and Denmark. The arrival of the Mustang III meant that the means to redress this deficiency was now available, and it resulted in the transfer of No 315 Sqn to Peterhead, on the northeast coast of Scotland in November 1944."
"One of its early operations came on the 7 November when seven Liberators were escorted to the Norwegian coast. Flt Sgt Ciundziewicki was lost when he went down to strafe a boat."
Although the book gives the date as 7 NOV, this seems to be the same incident.