Its interesting. Although I accept that the first issue of the metal wings in June 1944 did not include the 'S' wing, I've yet to come across a confirmed date of introduction for the metal 'S' wing into RNZAF service, or the 'S' wing in general, or confirmation that no 'S' wing was ever worn in metal unofficially.
In the case of the Royal Air Force the new 'S' wing was approved by the King under Kings Order 521 of 5th October 1943, after which it was passed to the Air Ministry who authorised the new category of 'Signaller' (not Air Signaller) in November 1943 under Air Ministry Order A.1242/43, which stated that the title 'Signaller' replaced the previous title of 'Wireless Operator / Air Gunner'. The associated 'S' half wing badge was not approved for wear by the Air Ministry until 6th January 1944, under Air Ministry Order A.3/44.
If the RNZAF approved the 'S' wing and/or 'Signaller' category prior to August 1945 wouldn't they have authorised a metal version too, not least as they aircraft such as the Lockheed Hudson and Beaufort operating in the Pacific?
I was also looking around to find an image of a post war 'S' wing and this site
https://www.jsmilitaria.com/royal-ne...air-force.html has the comment '
I also believe that there is a "S" half wing for Signaller in the Royal New Zealand Air Force, but these are rather scarce if its a WW2 era one. They seem to have been made from excess "N" or Navigators half wings, with an "S" added to the front, but you can still see the impression of the "N" to back.'
I have had a look at my four half wings (sorry, I forgot to photo the front!). The 'AG', 'E' and 'N' all have the 'M & K, W' marking. The 'S' wing seems cast aluminium, and if there was a marking in the normal place its covered by the lug. The lugs on the first three are circular and neatly attached, on the 'S' wing it is a U shape and not so cleanly attached (photo No. 3 with a comparison in No. 4). It doesn't appear to be a post war chromed type in either material or manufacture.