yes...concessions are good in BA, you get unlimited ID90s which means you pay 10% of the fare and the taxes: for example a return flight to Miami will cost you about 140 pounds. I always managed to find a seat and sometimes in a premium cabin.You also get staff tickets on all major airlines and five tickets on Oneworld for your family members.
You can also book ID80s which means your seat is guaranteed.
You can nominate three family members and they get the same conditions or your partner if you live together!