Yes it was an unfortunate accident. Jim did suffer a hand injury and our thoughts are with him and his family as it was a shock for us all. He was due to have an operation on his hand Sunday night but there were more urgent cases & so re-scheduled for tonight (Mon) so I'll should know more tomorrow.
I can confirm that Jim, an ex-officer is a qualified Pyrotechnic and experienced.
The emergency services were excellent, firstly another re-enactor an army medic helped him, followed by the Red Cross in just a few seconds as they were parked at the bottom of the arena, then the Ambulance and it just so happended that the Air Ambulance had been attending another incident nearby, so it made it look a bigger accident that it was.
Jim was his usual self cracking jokes, and asking for a roll-up while the oxygen mask was on!
As Bubba says, a load of cr*p, "5ft"!!! nor was it a grenade as reported elsewhere.