This was the designation of Allied military ferry convoys (together with a numerical suffix) plying the route from the the Clyde river in the UK to Narvik in northern Norway (April/May 1940).
There were only two such convoys, which delivered men, supplies and equipment to Norway in response to the German ‘Weserübung’ invasion. There were NP.1 of 11/15 April, and NP.3 of 13/17 May. The NP.1 convoy comprised the 14,287-ton Polish Batory, 11,442-ton Polish Chrobry, 21,833-ton British Empress of Australia, 22,424-ton British Monarch of Bermuda and 17,702-ton British Reina del Pacifico, and these were escorted at various stages of the undertaking by the battleship Valiant, battle-cruiser Repulse, light cruisers Birmingham, Cairo and Manchester, and destroyers Acasta, Amazon, Ardent, Brazen, Codrington, Fearless, Griffin, Highlander, Janus, Javelin, Juno, Protector, Vanoc, Vindictive, Volunteer, Whirlwind and Witherington. The NP.3 convoy comprised Batory and 11,030-ton Polish Sobieski, and these were escorted by the destroyers Antelope, Delight and French Milan.