BA have a (I think unpublished) benefit for their own Elite FFs that hold luggage can go up to 32kg, but this does NOT apply to other OW frequent flyers as discussed
here at post 2. That poster is a BA employee and knows her stuff, so please don't take it out on her.
It's one piece in economy. You can pay extra during online checkin to boost the weight to 32kg; you may be lucky at the airport and not have to.
That's life - it is economy, after all (and I write as a some time economy flyer).
Actually it is a published benefit, see:
http://www.britishairways.com/travel...searchResults#
http://www.britishairways.com/travel...=searchResults
Gold and Silver Executive Club members can carry 2 bags in all cabins, on all routes, unless the cabin allowance is greater. Each bag over 23kg and up to a maximum of 32kg is normally subject to a heavy bag charge which we will waive.