I booked a flight LHR-DUB-IAD for next summer in I class (all EI metal but BA flight numbers as I needed credit toward my 4 BA flights) - when I called to get seat assignments, the EI agent let me pick any seats I wanted for the DUB-IAD flight. For LHR-DUB, I looked at the seat map and it appeared to have the business class seats in the front, every single seat on the plane was empty. However, the agent told me (1) there was no business class on the plane and (2) in fact there were only three open seats left on the flight for next summer, in row 17 or something like that, and nothing else was available for assignment. I checked the seat map again after the call and it showed our three seats taken, and still every other seat on the plane unassigned so not sure what that was about.

I was going to give it another shot but based on this thread it sounds like I am not going to get business class on the LHR-DUB flight either way. Not a big deal on a short hop.