Yeah, the cage will be locked and bolted and basically glued to the house so that man or beast can't get in. Or, hopefully, out. We live in what I'd judiciously call 'a dodgy neighborhood', so it's always necessary to batten things down well. The more I think about it, the more I don't think the Beaks could possibly stick their dear little green heads out. Maybe Madge might try (she's already learned to open the current cage), but as you say, her head's too big to fit all the way through. It's not so much escape I'm worried about, but accidents (especially after poor Num Num's recent trouble).
I just realised, the cage includes a divider which allows it to be separated into two apartments. I might bring that inside and see how the Beaks measure up to it: it has the same spacing as the larger cage. That way, I'll have a better idea before I commit the birds to their outdoor life.
Gee! If the new cage is not suitable, I'll just have to get a Macaw or two to fill it up, won't I? Poor hubby will go spare! Then again... can't afford a Macaw... might have to get a couple of chooks instead...