Well I can confirm it's a Stirling! It was 'O - Orange', from 75 (NZ) Sqn, RAF, and was hit on a raid over Duisburg, on 26th April, 1943. The pic is from the Imperial War Museum, ref CE58.
The caption in my book only states 'Rear turret damage', and the above info. But, judging by the varied angles and sizes of the punctures, including those on the bulkhead inside the rear gunner's escape hatch, and the area of the spread, I'd say it was a flak burst.
I thought there was a little bit more of the rear of the aircraft visble in the photo in my book, but it's the same.