Hi Marlene
Is it because even though the DVD is called 'Top of the Tower' it was actually filmed at the bottom of the tower in the circus stalls/ring ???
I think he is just skitting (sorry!! bit of Lancashire twang entered there) that the curtain looks like it has stars on and they are pretending to be 'up the tower'. Like when he says about what a job it is getting all the animals in the lift!! I don't think it's that big up there (although I've never been... don't really fancy it).
Does this help??

maybe not!!
Anita