An interesting question Dave, although I think you may have answered it yourself. You have indicated that you wish to model both ships mid 42. Prior to September 1941 both ships were HMS, to which they would undoubtedly have flown the Union Jack and also the RN Ensign. This question is actually no consequence to you because they were recommissioned HMNZS in Sept 1941 and you will be modelling for mid 1942, after recommission as HMNZS they would fly the NZ Jack. There are No images, none I have seen, which show the Jack clearly flying for the period 1942. There are paintings which show the ship flying the NZ Jack in late 1939? but then that defies Admiralty and flag protocol doesn`t it.