British Airways have launched a generous promotion which gives you double Avios for up to 10 flights. This equates to 5 return flights if you are flying a straightforward A-B-A itinerary.
The flights need to be either BA operated, or BA marketed and operated by one of their Transatlantic partners: American Airlines, Iberia or Finnair. The flights must be done before 30th June 2020.
You must use this link AND book before 13th December 2019 to register, although you may as well register now via this link. The only reason you might want to delay registration is if you have a series of short haul flights first, then a series of longhaul. As you can only get double Avios on the first
Only some existing bookings will count. If you have booked something between 29th August – 18th September 2019, you can use this form to request retroactive registration of those flights. Be aware that you should carefully consider which bookings to register, as it's the first 10 sectors that get double Avios.
Once again, you must use this link to register.