Thank you Michael! I will pay closer attention to the legs next time I am unsure. I have edited the sighting and placed it in the Crabronidae family. Such a beautiful wasp!
Could it be Sericogaster fasciata? This was suggested on iNaturalist. This sighting was made 3 years ago in the same area of the Blue Mountains as I found it: https://www.inaturalist.org/taxa/1364013-Sericogaster-fasciata/browse_photos?place_id=6744
Very good! I have seen it once and should have remembered it. I am not the first to mistake it for a wasp. It was originally described as a wasp by Westwood in 1835.