It's an interesting case. I get slightly more seating, but when looking at fare buckets in EF (or elsewhere) it needs to be borne in mind that we are now 36 hours or so from departure, and that ticking clock needs to be factored into the equation. So my guess is that there are about 5 - 8 free seats in WT, a similar number in WTP, maybe slightly lower, 3 or 4 in CW and 1 in First. So yes Avios may be available but it wouldn't surprise me if there were only a few spare seats in each cabin at the time of departure. And also yes to the fact that the blocked seats appear to be pre-allocated to other passengers. So from this we can see that around a quarter of WT passengers either have status or have paid for seat, notably I would guess a family or two that paid for row 46 (or more likely perhaps, rang up to get the kids sat near to each parent). The blocked seats are preallocated to non status passengers, who in their MMB will only see one or no seating alternatives.

In other words, on first glance non status passengers really get clobbered by Theoretical Seating at T-72, however on a full flight the options for status passengers aren't that much better frankly. If BA sends out full aircraft there is a case for deploying status well before T-72 or buying a seat.

[Entirely as an aside, given this is a MF route, we can work out who is getting the champers in Y: rows 40 and 41, 43G, 44K and 45A!]

However this is likely to be a fast moving situation. I would check again every 3 hours or so, with a final check 27 hours before departure (since the seating will go offline for an hour or two before OLCI), and hopefully something better will come up. If you are not in O I would ring up for a UuA since you could end up further forward in the end.