Originally Posted by danwer930

That makes sense EXCEPT for two reasons: First, the morning flight from EWR-LHR is somewhat unique in that a lot of people take it (as I do) expressly to avoid a redeye and the jetlag that goes with it. The only other flights UA offers on that route are all redeyes. So it's not a matter of getting in just a couple hours later like you would on, say, EWR-LAX.

Second, according to the previous 764 Seatmap 3 days ago, the flight was nearly full in all cabins. I saw maybe 10 open seats or so total. So it doesn't seem like the change was made because of too many open seats in back, and that's a lot of reaccomodating they'll need to do if they're swapping out a widebody for a narrow-body.

Called Premier Desk this morning - they are still perplexed about what's going on and the website is still listing the flight as a 764 while showing a 752 seatmap right below it. I'm taking my chances on 21A which does still exist in E+ even if it ends up being a 764 after all. We'll see what happens!