perhaps its protectionism of British poultry producers who can't compete with Americans, who knows
As Ive pointed out, there is no rational basis for such a ban. Theyre eating other food subject to the same process right now. There is no scientific evidence from the US to support any claim that the process is unsafe.
IF they want to keep this in place in the teeth of all that, they can but there will obviously be a give and take. Theyll likely have to accept some American protectionist measure on something that theyd prefer not to see in place. That is the stuff of negotiation. It doesnt have to be that complicated or take that long if both sides want a deal done.