(1) Part 1 shall not extinguish or abridge any powers or authorities which, if this Act had not been passed, would have been exercisable by virtue of the prerogative of the Crown, or any powers or authorities conferred on the Crown by any Statute, and in particular, nothing in the said Part 1 shall extinguish or abridge any powers or authorities exercisable by the Crown, whether in time of peace or of war, for the purpose of the defence of the realm or of training or maintaining the efficiency of, any of the armed forces of the Crown.