In order to qualify you must pre-register at ba.com before booking any flights.
The offer applies to all British Airways operated flights from the U.K. as well as flights booked under a BA code and operated by American Airlines, Finnair, and Iberia between Europe, Norway, Switzerland and North America, Mexico and Puerto Rico. It also applies to services operated by BA subsidiary OpenSkies from Paris Orly and Newark and flights operated by BA franchise partner SUNAIR of Scandinavia.
It does not apply to flights operated by other BA franchises such as Comair in South Africa, nor flights operated by other IAG airlines, Oneworld alliance partners or other BA codeshare partners.
The offer is not open to members of the Executive Club in the USA, Canada, Mexico and South Africa.
If you are not a member of the Executive Club you can sign up at ba.com