@Sadie, at least you're not using the notion that they used the window.
I always said that it couldn't be done with such a narrow window, but having seen CB and read about him and his scaling buildings to get in via windows, I must admit I have modified my views a little. He is like a circus act by the sounds of it. He is so skinny and obviously used to getting thru' small spaces, I wonder now..
Please do not take it that I am accusing CB. I am not but am open to the fact that if anyone could, he could.
Personally I believe that access was via the front door using a key and quite possibly never touching the door with the hands but using the key to open and close it (push / pull) as well a unlock it.
Because of that, I am not able to define exactly how the perp entered, but I definitely believe it was via the fronmt door. Deeply recessed, out of sight and very dark in there. I seem to remember that the porch light was broken. Please correct me if I am wrong on that.
I certainly believe that Madeleine was not passed through the window, too awkward, no footspace for the lifter.. She went out with the perp via the front door IMO and was passed to Tannerman at that stage. CB could have been the enterer and lifter, but we dont know for certain.
When lifted, her head would have been on the lifters right arm. With her head being on the left arm of Tannerman, this indicates that she had been passed by someone to Tannerman.
I dont know why we keep on about Tannerman not looking like, or alternatively looking like CB, cos it appears that she was passed to a second person, who likely was not CB.
I think that the front door was used both for entrance and departure.