Originally Posted by
blindy
So if I wanted to upgrade WT+ to CW, there needs to be Avios availability in both the classes on the same flight. Can someone confirm this please?
Nope, there doesn't.
Go to Avios.com and play with their system. If an Avios flight is available in CE, WTP or CW (not First) it's eligible.
It's effectively an "Avios saver" ticket. CW is 50K Avios rather than 100K, for example.