Just for illustration purposes....have an open-jaw ticket for next month, going LHR-IAD, MIA-LHR.

Managed to upgrade WTP-CW last month for the IAD leg, which was 10K avios and £53 for YQ. When I upgraded MIA-LHR this morning, it cost me 12.5K avios and £71 for YQ. I thought it would be the same price for each as a US return but IAD/MIA are in different sectors, apparently.