Thanks for the steer, I'll wait for the photos.
I was stood next to the Canberra T17 when the armourer Ted T****r(?) fired the seat in the hangar at Wyton in the early 80's. And stood in the bomb bay when the electrician J**n L****t fired the canopy dets. Maybe that's why I'm deaf.
Both incidents had about 4 bits of swiss cheese lining up.
But this must be a world record. Murphy's Law must come into effect after 10 bits of cheese, and this is more than 20 !