I have been looking on BA.com to see if I could use some of my avios on a trip to the USA. I looked at reward availabilty in CW and decided to see which method (all avios or UUA) would give me best value.

However, if I go to book UUA from DUB-LHR-ATL base fare is €1125.
Selecting the exact same flights for UUA give a base fare of £968.

I would expect that the taxes and charges would be different for the higher cabin but not the base fare and certainly not £120.

Is there an underlying reason for this?