It was overcrowded as the bees from the one next door had absconded due to a Virgin queen disappearing and seem to have piled into this one. I lowered the numbers by introducing another virgin into the failed one and moving them around.
I had a look regarding CBVP and although it looks like it from the photograph they don't have the shiny/greasy appearance described by most. There is also no shaking, they just appear vey lethargic. I'm starting to wonder if they are simply old bees. Thinking back the original bees have been in this Apidea for nearly a month.