I have just found some more information on the ASR markings and have revised my original notes on the colours thereof.In response to a query from RNZAF Fiji late in 1947, Air Department ascertained that the Air Sea Rescue aircraft should carry distinctive ICAO markings. The markings comprised the application of "orange yellow" to the aircraft plus a "large yellow cross". The reference was ICAO Doc. 2480, and this contained a drawing of the cross but no dimensions. The disc on which the cross was superimposed specified as black. Air Department decided that rather than wait for ICAO to be more specific the RNZAF Air Sea Rescue Hudsons-which carried airborne lifeboats- would have their RNZAF roundels in all positions by discs of equivalent diameter. Accordingly an instruction was issued to Wigram, Ohakea, Hobsonville and Fiji on 10 November 1947 for the change to be carried out "as soon as possible and not later than the next minor inspection". The instruction, and later Air Department Order, included an undimensioned sketch based on the ICAO drawing, and this gave a cross whose width (thickness) was about 22% of the roundel diameter. This is borne out by the photographs of NZ2016 and NZ2085 (see below, close up is NZ 2085 taken in the first half of 1948, roundel diameter appears to be 36 inches with the cross bars 8 inches thick) but the inevitable exception appears on NZ2063 where the cross is much thinner, about 15%.
The RNZAF instructions in all cases specified black for the disc. I can find no information to indicate when the ASR roundel became obsolete.