Give me a min...off to look at photo thread.... 
Blimey! You're right.

There is what looks like a door behind that tree, and in JB's hand-drawn plan it does say 'bolts', with a doorway drawn on, in between the words 'stairs' and 'scullery'. (No, I can't do link - look for yourselves.)
But, still, what does this prove? Except for another way the police could have gained entry.