On Monday 9 new handling staff started at Manston.
The passenger routes are a bit slow in developing, but I think that's true of all 3 of the active European airports (the UK is in Europe). If anything I think the other two are not growing at all, and Manston has shot past Prestwick in terms of cargo tonnage. Their non-European airports are struggling too. Perhaps they're just not very good at running them.
I heard recently that Infratil think they paid too much for Manston, but that's in the past.