I flew BEG-LHR-BEG on a few occasions since the service restarted, and I've never seen less than 6 rows at the front, clearly there is some degree of appeal on the part of the business clientele. LH/OS are, historically (and unlike BA), big players in the Balkans, meaning no solid ground for comparison in relation to this particular market (although, given the choice, I would be scheduling travel on one of those days when BA operates, merely to avoid the joys of connecting at FRA, not to mention LH's ghastly product...). Air Serbia is a decent, tiny airline, featuring (as you would expect) a robust network in the region, they will compete on the point-to-point, and surely appeal to those travelling further afield in Southeastern Europe. OT aside and going back to the BA service, I see this is now a year-round service, which is good news (as far as I remember, it was only scheduled to be seasonal/winter only).