Well, somebody who went to the BB Launch Night Project said that Justin and Alan were in a tour of the house, and there were two staircases, curved, with the Diary Room being in the middle.
I just drawed what I read, I think its about 70% right in terms of structure, as for decoration I just guessed that!
The last time the staircase was seen other than Evicitons/Launch was during BB3 when the staircase was freely avalible to run up and down etc.
It's going to be interesting, especially this two staircases lark, I don't know if I like that idea