Thanks for the kind words chaps.
Dennis, yes, I fitted the the two cannons.
In period pics, the cannon ports are visible, although of course that's no guarantee that the weapons were installed. However. the account of this particular operation, by the pilot, although not confirming that they were fitted, hints that they were. Contrary to some descriptions of the rear MG15 being removed on these aircraft for this mission, this was in place, and used on this operation.