I have been looking on the seatmaps on EF and the show 2 rows for J and all the rows behind up to 8 (EF shows as Y) as having 5 out of the 6 seats blocked. Can someone please explain this? I have a sneaking suspicion they become J seats, but how can Y seats have the legroom to be counted as J. Hmm sneaky BA!!?
Btw please excuse my BA ignorance, mostly fly AA now!

Thanks.