Gentlemen, thank you all for your input!

Jerry, I see where you’re “aiming at” with your 20 mm cannon suggestion but as pointed out by Martin that was a field mod by I believe a South African unit in the Western Desert, the gun being installed internally and poking through the bomb aiming window in the nose. Must have put quite a strain on the nose structure! Also, the Blens in the still are all bombers of course.

Mothminor, thanks for that Alamy photo link and the extra info it gives. Something concocted on Sqn level perhaps? Must have created an awful lot of extra drag compared to the standard blister and the FN54A turret though. Just wondering if the observer could sit/lie facing backwards in that tub so as to operate the gun in a “normal” manner, normal as opposed to trying to aim via a mirror system as in the blister and FN54A.

Quite intriguing, isn’t it :)?

Cheers,
Walter