I also can't recall the Adria flights having been advertised in the UK. My family and I took the flight last week and will be returning next Tuesday, but the only reason we knew about it is the fact that I read Pprune and we saw it in the Echo. Northern Slovenia and Styria are not exactly the most famous destinations amongst Brits so coupled with the late arrival time in MBX (which I speak from personal experience was brutal when we had some distance still to travel by road), I don't think conditions are conducive to attracting British passengers in significant numbers. Having said that, the load factor was very high on the outbound and the return seems to be full so hopefully Adria will be pleased with that, assuming yields are also good.