It's an old expression, and It's one I'm quite fond of for some reason. The basic, long winded meaning would be:
"The event that we we were hoping would not affect us did not, indeed, affect us. Therefore, the threshold by which it did not effect us is no concern; It could be very large or very small, but I don't give a pair of dingoes kidneys how close of a shave it was. It missed us, and the amount of distance it missed us by it really not that important."