British Airways Refund Rules

If a delay or cancellation of five hours or more disrupts a connecting flight that you booked under the same booking reference (with a planned connection time of 24 hours or less) and you no longer wish to continue to your final destination, the operating carrier will provide you with a return flight to your original point of departure at the earliest opportunity as well as refund the parts of the journey you did not fly.

You can claim a refund for the parts of your journey which you did fly, provided that you can prove that the journey no longer serves any purpose in relation to your original travel plans. You must then claim this refund at the same time as claiming a refund for the parts of your journey you did not fly.

To claim a refund, please follow the same steps as for cancelled flights.