8 wide, but more space forward/back than some other carriers. Total seat space I think is roughly on par with other carriers, which may be 4 or 6 across but seat pitch is less by sneaking feet under the seat in front for example, or having seats on an angle.
I think it's a long way short of the space you get on SQ. No way can BA squeeze in 8 seats whereas SQ has just 4 and both airlines are "on par" in terms of space. For that to happen SQ would have to have twice the amount of rows installed across the dame distance.