Ancient Aviator
My apologies, I should have replied yesterday.
You asked " Did not Day go outside his remit?". I fail to see how he could do so as it was his Board of Inquiry - constituted by him. If, following investigation by the Board (who investigate on his behalf), it is apparent that further matters require investigation then (to borrow the favourite phrase of current incumbant at 10 Downing Street) it is "right and proper" to adjust the Terms of Reference if necessary.