Basic fluid mechanics dear b******d up by liquids being incompressible and gases not so.
However the wind itself does not have to directly move the door or curtains. It can do so by causing a venturi effect.
Do we know in which direction the curtains were alleged to have whooshed ? ie inwards outwards or sideways?
Aw Gawd, it is 55 years since I knew about the Venturi effect. Have forgotten all that stuff, something to do with a narrow orifice and its effect on flow, if I remember correctly.
Must have a chat with hubby, he will remember
My understanding is that the curtains whooshed inwards and the door slammed the same way at about 10pm.
Whilst early on, the door opened in the opposite direction, BUT it could be that, early on, the window had NOT been opened yet..
Could have been, of course, that the door was opened by Madeleine popping to the loo, or an intruder.
.... or even as Pegasus thinks, but I think he has it wrong tbh