BA’s equivalent of oneworld Emerald is BA Gold. There are variations above this, but it is generally seen as the top tier for most benefits. Important amongst these is advance seat selection, including exit rows.
The BA web site describes the benefit thus:
Free seat selection at the time of booking for everyone in your travel party, whatever cabin you’re travelling in (except on hand baggage only fares). This even includes family or friends on other bookings as long as they’re travelling in the same cabin and on the same flight
However, today seems to mark an unannounced change whereby exit row seats can no longer be selected by Golds in advance. There are some suggestions that there will be an option 72 hours before departure, but I haven’t seen that yet as my flights are some weeks away.
My example is from a flight to Berlin in late March where the Club Europe section extends to the exit row on the A321. As you can see below from Expert Flyer, the exit row seats are blocked, not booked:
The BA web site seat plan shows this:
This is when I am logged in as a BA Gold Guest List member. Compare Row 1, where 1D is available to me on the BA site, against on Expertflyer where it is blocked. In theory the other blocked seats in Rows 8 and 9 should be available to me.
Unless BA has made a change!
People are speculating that with the awful legroom on BA now, people are picking EuroTraveller exit rows rather than Club Europe and they could be right. The next few days will reveal whether access to these exit rows suddenly become available but chargeable.