GBP2600 on LHR-IST does not sound like an O class fare (unless you have a weird and wonderful routing).I would have thought that at least one leg must be in C or J at that price level if the routing is a plain vanilla LHR-CDG-IST or LHR-AMS-IST.

Fabo.sk is correct that O class is used both for awards and deep discount business class fares on AF/KL. He is also correct that this has been true for many years and that it is not unknown on other airlines to have deep discounted business class fares not earning on partner airlines. There was not any arrogance in there and that comment is rather uncalled for.