Thanks everyone
Ezil, It's growing in moss on my windowledge. I had my previous two in the green house last year but they didn't like the cold over the winter (it's a cool growing greenhouse). I moved the surviving one into my house in the spring and that's grown well there, this one has seemed happy enough as well, although not doing much till now.
It's an East windowledge behind a sheer curtain and it seems happy with light levels (the surviving one from last year had gone pale yellow and red in the greenhouse, but the green colour has come back since moving it inside.
I don't do anything special with humidity for these, just try and keep the moss always a little damp.