Well, anyone with the slightest knowledge of a Firefly & warbirds in general would know they're not fitted with ejector seats. I copied this from the Sky News site.
An air show spokeswoman said officials were trying to piece together what had gone wrong.
The plane was understood to have just completed an aerobatic display and was returning to land.
Apparently the wreckage ended up in a field on the other side of the M11 motorway. This runs very close to the end of the Duxford runway but I would have thought if it happened during the display it would have crashed on the airfield itself.
I'm speculating now. My sympathy goes to the relatives of the crew. I have only disgust for the insensitivity of the media for repeatedly showing those clips - possibly before they were informed.