During 1957, the fate of the SR.177 was to be subject to a massive re-thinking of air defence philosophy in Britain, being principally outlined in the 1957 Defence White Paper, which called for manned combat aircraft to be replaced by missiles. Very shortly afterwards, OR.337 was cancelled and the prospects of an order from the RAF had evaporated. This was a serious blow, while it the Royal Navy and Germany remained potential customers for the SR.177, the confidence of both parties was shaken by the move.