Sorry if this is a question covered elsewhere. I am a regular reader but it’s my first time posting.
I am BA bronze and only travel for leisure but I have noticed that flights departing from CDG or FRA via Heathrow are much cheaper than booking to leave from Heathrow.
Is there any rule that stops me buying, say CDG-KUL and not taking the flight from CDG to Heathrow? This would save me £250 rtn in WT+ and also allow me to use Avios to upgrade.