I handled that in my Morning Brief.....with a statement to the Gunners along the lines of " If we are getting the sh%t shot out of us and you see where it is coming from.....kill those SOB's!
My comment about requesting approval from the chain of command above the Aircraft Commander is what I was referring to....and by telling the gunners for the situation described above they had my permission to return fire.
If my superiors could delegate that authority to me....it seemed logical I could delegate that authority to the gunner and by adding my. own limitations it was still within the ROE.
I saw that as being part of the Army Concept of the Commander's Brief where he lets the Troops in on what the upcoming Mission was supposed to accomplish so they could carry it out even if direct Command and Control was lost for some reason during contact with the Enemy.
Sounds like the UK Rules covers that as part of your ROE.....which seems right and logical.