Which airlines and cabins can I use my Companion Voucher on?

Companion Vouchers can be used on Reward Flights operated by British Airways, Iberia and Aer Lingus. BA American Express Credit Card Companion Vouchers are valid for 12 months, can only be used in Economy, and are subject to Reward Flight availability. BA American Express Premium Plus Companion Vouchers are valid for 24 months, can be used in any cabin including First, are subject to Reward Flight availability, and offer enhanced Reward Flight availability in Club World.