Originally Posted by
lhrsfo
This is the slight problem with the extra seat route - it will inevitably be shared with another person, even if you have bought it. You then have a choice whether to get irritated by this, or just accept it and enjoy the karma.
Shared how? If you've paid for the seat and have a boarding pass for it the seat is yours. There should be no hesitation in explaining that to another passenger.
European business class is different because both of you have paid for the extra space and the middle seat is "shared."